예제 #1
0
        static void VdbeSorterCompare(VdbeCursor cursor, bool omitRowid, string key1, int key1Length, string key2, int key2Length, ref int out_)
        {
            KeyInfo        keyInfo = cursor.KeyInfo;
            VdbeSorter     sorter  = (VdbeSorter)cursor.Sorter;
            UnpackedRecord r2      = sorter.Unpacked;

            if (key2 != null)
            {
                Vdbe.RecordUnpack(keyInfo, key2Length, key2, r2);
            }
            if (omitRowid)
            {
                r2.Fields = keyInfo.Fields;
                Debug.Assert(r2.Fields > 0);
                for (int i = 0; i < r2.Fields; i++)
                {
                    if ((r2.Mems[i].Flags & MEM.Null) != 0)
                    {
                        out_ = -1;
                        return;
                    }
                }
                r2.Flags |= UNPACKED.PREFIX_MATCH;
            }
            out_ = Vdbe.RecordCompare(key1Length, key1, r2);
        }
예제 #2
0
파일: Vdbe.cs 프로젝트: BclEx/GpuStructs
        public RC Exec()
        {
            VdbeOp[] ops = Ops.data; // Copy of p.aOp
            VdbeOp op; // Current operation
            RC rc = RC.OK; // Value to return
            Context ctx = Ctx; // The database
            byte resetSchemaOnFault = 0; // Reset schema after an error if positive
            TEXTENCODE encoding = E.CTXENCODE(ctx); // The database encoding
            Mem[] mems = Mems.data; // Copy of p.mems
            Mem in1 = null; // 1st input operand
            Mem in2 = null; // 2nd input operand
            Mem in3 = null; // 3rd input operand
            Mem out_ = null; // Output operand
            int compare = 0;  // Result of last OP_Compare operation
            int[] permutes = null; // Permutation of columns for OP_Compare
            long lastRowid = ctx.LastRowID; // Saved value of the last insert ROWID

            //// INSERT STACK UNION HERE ////
            Debug.Assert(Magic == VDBE_MAGIC_RUN); // sqlite3_step() verifies this
            Enter();
            if (RC_ == RC.NOMEM)
                goto no_mem; // This happens if a malloc() inside a call to sqlite3_column_text() or sqlite3_column_text16() failed.
            Debug.Assert(RC_ == RC.OK || RC_ == RC.BUSY);
            RC_ = RC.OK;
            Debug.Assert(HasExplain == 0);
            ResultSet = null;
            ctx.BusyHandler.Busys = 0;
            if (ctx.u1.IsInterrupted) goto abort_due_to_interrupt; //CHECK_FOR_INTERRUPT;
#if !OMIT_TRACE && ENABLE_IOTRACE
            IOTraceSql();
#endif
#if !OMIT_PROGRESS_CALLBACK
            bool checkProgress = (ctx.Progress != null); // True if progress callbacks are enabled
            int progressOps = 0; // Opcodes executed since progress callback.
#endif
#if DEBUG
            C._benignalloc_begin();
            if (PC == 0 && (ctx.Flags & Context.FLAG.VdbeListing) != 0)
            {
                Console.Write("VDBE Program Listing:\n");
                PrintSql();
                for (int i = 0; i < Ops.length; i++)
                    PrintOp(Console.Out, i, Ops[i]);
            }
            C._benignalloc_end();
#endif
            int pc = 0; // The program counter
            for (pc = PC; rc == RC.OK; pc++)
            {
                Debug.Assert(pc >= 0 && pc < Ops.length);
                if (ctx.MallocFailed) goto no_mem;
#if VDBE_PROFILE
                int origPc = pc; // Program counter at start of opcode
                ulong start = _hwtime(); // CPU clock count at start of opcode
#endif
                op = ops[pc];

#if DEBUG
                // Only allow tracing if SQLITE_DEBUG is defined.
                if (Trace != null)
                {
                    if (pc == 0)
                    {
                        Console.Write("VDBE Execution Trace:\n");
                        PrintSql();
                    }
                    PrintOp(Trace, pc, op);
                }
#endif

#if TEST
                // Check to see if we need to simulate an interrupt.  This only happens if we have a special test build.
                if (g_interrupt_count > 0)
                {
                    g_interrupt_count--;
                    if (g_interrupt_count == 0)
                        Main.Interrupt(ctx);
                }
#endif

#if !OMIT_PROGRESS_CALLBACK
                // Call the progress callback if it is configured and the required number of VDBE ops have been executed (either since this invocation of
                // sqlite3VdbeExec() or since last time the progress callback was called). If the progress callback returns non-zero, exit the virtual machine with
                // a return code SQLITE_ABORT.
                if (checkProgress)
                {
                    if (ctx.ProgressOps == progressOps)
                    {
                        int prc = ctx.Progress(ctx.ProgressArg);
                        if (prc != 0)
                        {
                            rc = RC.INTERRUPT;
                            goto vdbe_error_halt;
                        }
                        progressOps = 0;
                    }
                    progressOps++;
                }
#endif

                // On any opcode with the "out2-prerelease" tag, free any external allocations out of mem[p2] and set mem[p2] to be
                // an undefined integer.  Opcodes will either fill in the integer value or convert mem[p2] to a different type.
                Debug.Assert(op.Opflags == g_opcodeProperty[op.Opcode]);
                if ((op.Opflags & OPFLG.OUT2_PRERELEASE) != 0)
                {
                    Debug.Assert(op.P2 > 0);
                    Debug.Assert(op.P2 <= Mems.length);
                    out_ = mems[op.P2];
                    MemAboutToChange(this, out_);
                    MemRelease(out_);
                    out_.Flags = MEM.Int;
                }

#if DEBUG
                // Sanity checking on other operands
                if ((op.Opflags & OPFLG.IN1) != 0)
                {
                    Debug.Assert(op.P1 > 0);
                    Debug.Assert(op.P1 <= Mems.length);
                    Debug.Assert(E.MemIsValid(mems[op.P1]));
                    REGISTER_TRACE(this, op.P1, mems[op.P1]);
                }
                if ((op.Opflags & OPFLG.IN2) != 0)
                {
                    Debug.Assert(op.P2 > 0);
                    Debug.Assert(op.P2 <= Mems.length);
                    Debug.Assert(E.MemIsValid(mems[op.P2]));
                    REGISTER_TRACE(this, op.P2, mems[op.P2]);
                }
                if ((op.Opflags & OPFLG.IN3) != 0)
                {
                    Debug.Assert(op.P3 > 0);
                    Debug.Assert(op.P3 <= Mems.length);
                    Debug.Assert(E.MemIsValid(mems[op.P3]));
                    REGISTER_TRACE(this, op.P3, mems[op.P3]);
                }
                if ((op.Opflags & OPFLG.OUT2) != 0)
                {
                    Debug.Assert(op.P2 > 0);
                    Debug.Assert(op.P2 <= Mems.length);
                    MemAboutToChange(this, mems[op.P2]);
                }
                if ((op.Opflags & OPFLG.OUT3) != 0)
                {
                    Debug.Assert(op.P3 > 0);
                    Debug.Assert(op.P3 <= Mems.length);
                    MemAboutToChange(this, mems[op.P3]);
                }
#endif

                // What follows is a massive switch statement where each case implements a separate instruction in the virtual machine.  If we follow the usual
                // indentation conventions, each case should be indented by 6 spaces.  But that is a lot of wasted space on the left margin.  So the code within
                // the switch statement will break with convention and be flush-left. Another big comment (similar to this one) will mark the point in the code where
                // we transition back to normal indentation.
                //
                // The formatting of each case is important.  The makefile for SQLite generates two C files "opcodes.h" and "opcodes.c" by scanning this
                // file looking for lines that begin with "case OP_".  The opcodes.h files will be filled with #defines that give unique integer values to each
                // opcode and the opcodes.c file is filled with an array of strings where each string is the symbolic name for the corresponding opcode.  If the
                // case statement is followed by a comment of the form "/# same as ... #/" that comment is used to determine the particular value of the opcode.
                //
                // Other keywords in the comment that follows each case are used to construct the OPFLG_INITIALIZER value that initializes opcodeProperty[].
                // Keywords include: in1, in2, in3, out2_prerelease, out2, out3.  See the mkopcodeh.awk script for additional information.
                //
                // Documentation about VDBE opcodes is generated by scanning this file for lines of that contain "Opcode:".  That line and all subsequent
                // comment lines are used in the generation of the opcode.html documentation file.
                //
                // SUMMARY:
                //
                //     Formatting is important to scripts that scan this file.
                //     Do not deviate from the formatting style currently in use.
                switch (op.Opcode)
                {
                    case OP.Goto: // jump
                        {
                            // Opcode:  Goto * P2 * * *
                            //
                            // An unconditional jump to address P2. The next instruction executed will be 
                            // the one at index P2 from the beginning of the program.
                            if (ctx.u1.IsInterrupted) goto abort_due_to_interrupt; //CHECK_FOR_INTERRUPT;
                            pc = op.P2 - 1;
                            break;
                        }
                    case OP.Gosub: // jump
                        {
                            // Opcode:  Gosub P1 P2 * * *
                            //
                            // Write the current address onto register P1 and then jump to address P2.
                            in1 = mems[op.P1];
                            Debug.Assert((in1.Flags & MEM.Dyn) == 0);
                            MemAboutToChange(this, in1);
                            in1.Flags = MEM.Int;
                            in1.u.I = pc;
                            REGISTER_TRACE(this, op.P1, in1);
                            pc = op.P2 - 1;
                            break;
                        }
                    case OP.Return:  // in1
                        {
                            // Opcode:  Return P1 * * * *
                            //
                            // Jump to the next instruction after the address in register P1.
                            in1 = mems[op.P1];
                            Debug.Assert((in1.Flags & MEM.Int) != 0);
                            pc = (int)in1.u.I;
                            break;
                        }
                    case OP.Yield: // in1
                        {
                            // Opcode:  Yield P1 * * * *
                            //
                            // Swap the program counter with the value in register P1.
                            in1 = mems[op.P1];
                            Debug.Assert((in1.Flags & MEM.Dyn) == 0);
                            in1.Flags = MEM.Int;
                            int pcDest = (int)in1.u.I;
                            in1.u.I = pc;
                            REGISTER_TRACE(this, op.P1, in1);
                            pc = pcDest;
                            break;
                        }
                    case OP.HaltIfNull: // in3
                        {
                            // Opcode:  HaltIfNull  P1 P2 P3 P4 *
                            //
                            // Check the value in register P3.  If it is NULL then Halt using parameter P1, P2, and P4 as if this were a Halt instruction.  If the
                            // value in register P3 is not NULL, then this routine is a no-op.
                            in3 = mems[op.P3];
                            if ((in3.Flags & MEM.Null) == 0) break;
                            goto case OP.Halt;
                        }
                    // Fall through into OP_Halt
                    case OP.Halt:
                        {
                            // Opcode:  Halt P1 P2 * P4 *
                            //
                            // Exit immediately.  All open cursors, etc are closed automatically.
                            //
                            // P1 is the result code returned by sqlite3_exec(), sqlite3_reset(), or sqlite3_finalize().  For a normal halt, this should be SQLITE_OK (0).
                            // For errors, it can be some other value.  If P1!=0 then P2 will determine whether or not to rollback the current transaction.  Do not rollback
                            // if P2==OE_Fail. Do the rollback if P2==OE_Rollback.  If P2==OE_Abort, then back out all changes that have occurred during this execution of the
                            // VDBE, but do not rollback the transaction. 
                            //
                            // If P4 is not null then it is an error message string.
                            //
                            // There is an implied "Halt 0 0 0" instruction inserted at the very end of every program.  So a jump past the last instruction of the program
                            // is the same as executing Halt.
                            if (op.P1 == (int)RC.OK && Frames != null)
                            {
                                in3 = mems[op.P3];
                                // Halt the sub-program. Return control to the parent frame.
                                VdbeFrame frame = Frames;
                                Frames = frame.Parent;
                                FramesLength--;
                                SetChanges(ctx, Changes);
                                pc = FrameRestore(frame);
                                lastRowid = ctx.LastRowID;
                                if (op.P2 == (int)OE.Ignore)
                                {
                                    // Instruction pc is the OP_Program that invoked the sub-program currently being halted. If the p2 instruction of this OP_Halt
                                    // instruction is set to OE_Ignore, then the sub-program is throwing an IGNORE exception. In this case jump to the address specified
                                    // as the p2 of the calling OP_Program.
                                    pc = Ops[pc].P2 - 1;
                                }
                                ops = Ops.data;
                                mems = Mems.data;
                                break;
                            }

                            RC_ = (RC)op.P1;
                            ErrorAction = (OE)op.P2;
                            PC = pc;
                            if (op.P4.Z != null)
                            {
                                Debug.Assert(RC_ != RC.OK);
                                C._setstring(ref ErrMsg, ctx, "%s", op.P4.Z);
                                C.ASSERTCOVERAGE(SysEx._GlobalStatics.Log != null);
                                SysEx.LOG((RC)op.P1, "abort at %d in [%s]: %s", pc, Sql_, op.P4.Z);
                            }
                            else if (RC_ != 0)
                            {
                                C.ASSERTCOVERAGE(SysEx._GlobalStatics.Log != null);
                                SysEx.LOG((RC)op.P1, "constraint failed at %d in [%s]", pc, Sql_);
                            }
                            rc = Halt();
                            Debug.Assert(rc == RC.BUSY || rc == RC.OK || rc == RC.ERROR);
                            if (rc == RC.BUSY)
                                RC_ = rc = RC.BUSY;
                            else
                            {
                                Debug.Assert(rc == RC.OK || RC_ == RC.CONSTRAINT);
                                Debug.Assert(rc == RC.OK || ctx.DeferredCons > 0);
                                rc = (RC_ != 0 ? RC.ERROR : RC.DONE);
                            }
                            goto vdbe_return;
                        }
                    case OP.Integer: // out2-prerelease
                        {
                            // Opcode: Integer P1 P2 * * *
                            //
                            // The 32-bit integer value P1 is written into register P2.
                            out_.u.I = op.P1;
                            break;
                        }
                    case OP.Int64: // out2-prerelease
                        {
                            // Opcode: Int64 * P2 * P4 *
                            //
                            // P4 is a pointer to a 64-bit integer value. Write that value into register P2.
                            Debug.Assert(op.P4.I64 != 0);
                            out_.u.I = op.P4.I64;
                            break;
                        }
#if !OMIT_FLOATING_POINT
                    case OP.Real: // same as TK_FLOAT, out2-prerelease
                        {
                            // Opcode: Real * P2 * P4 *
                            //
                            // P4 is a pointer to a 64-bit floating point value. Write that value into register P2.
                            out_.Flags = MEM.Real;
                            Debug.Assert(!double.IsNaN(op.P4.Real));
                            out_.R = op.P4.Real;
                            break;
                        }
#endif
                    case OP.String8:// same as TK_STRING, out2-prerelease
                        {
                            // Opcode: String8 * P2 * P4 *
                            //
                            // P4 points to a nul terminated UTF-8 string. This opcode is transformed into an OP_String before it is executed for the first time.
                            Debug.Assert(op.P4.Z != null);
                            op.Opcode = OP.String;
                            op.P1 = op.P4.Z.Length;
#if !OMIT_UTF16
                            if (encoding != TEXTENCODE.UTF8)
                            {
                                rc = MemSetStr(out_, op.P4.Z, -1, TEXTENCODE.UTF8, C.DESTRUCTOR_STATIC);
                                if (rc == RC.TOOBIG) goto too_big;
                                if (ChangeEncoding(out_, encoding) != RC.OK) goto no_mem;
                                Debug.Assert(out_.Malloc == out_.Z);
                                Debug.Assert((out_.Flags & MEM.Dyn) != 0);
                                out_.Malloc = null;
                                out_.Flags |= MEM.Static;
                                out_.Flags &= ~MEM.Dyn;
                                if (op.P4Type == Vdbe.P4T.DYNAMIC)
                                    C._tagfree(ctx, ref op.P4.Z);
                                op.P4Type = P4T.DYNAMIC;
                                op.P4.Z = out_.Z;
                                op.P1 = out_.N;
                            }
#endif
                            if (op.P1 > ctx.Limits[(int)LIMIT.LENGTH])
                                goto too_big;
                            goto case OP.String;
                        }
                    // Fall through to the next case, OP_String
                    case OP.String: // out2-prerelease
                        {
                            // Opcode: String P1 P2 * P4 *
                            //
                            // The string value P4 of length P1 (bytes) is stored in register P2.
                            C._free(ref out_.Z_);
                            Debug.Assert(op.P4.Z != null);
                            out_.Flags = MEM.Str | MEM.Static | MEM.Term;
                            out_.Z = op.P4.Z;
                            out_.N = op.P1;
                            out_.Encode = encoding;
                            UPDATE_MAX_BLOBSIZE(out_);
                            break;
                        }
                    case OP.Null: // out2-prerelease
                        {
                            // Opcode: Null P1 P2 P3 * *
                            //
                            // Write a NULL into registers P2.  If P3 greater than P2, then also write NULL into register P3 and every register in between P2 and P3.  If P3
                            // is less than P2 (typically P3 is zero) then only register P2 is set to NULL.
                            //
                            // If the P1 value is non-zero, then also set the MEM_Cleared flag so that NULL values will not compare equal even if SQLITE_NULLEQ is set on OP_Ne or OP_Eq.
                            int cnt = op.P3 - op.P2;
                            Debug.Assert(op.P3 <= Mems.length);
                            MEM nullFlag;
                            out_.Flags = nullFlag = (op.P1 != 0 ? (MEM.Null | MEM.Cleared) : MEM.Null);
                            while (cnt > 0)
                            {
                                out_++;
                                MemAboutToChange(this, out_);
                                MemRelease(out_);
                                out_.Flags = nullFlag;
                                cnt--;
                            }
                            break;
                        }
                    case OP.Blob:  // out2-prerelease
                        {
                            // Opcode: Blob P1 P2 * P4
                            //
                            // P4 points to a blob of data P1 bytes long.  Store this blob in register P2.
                            Debug.Assert(op.P1 <= CORE_MAX_LENGTH);
                            MemSetStr(out_, op.P4.Z, op.P1, 0, null);
                            out_.Encode = encoding;
                            UPDATE_MAX_BLOBSIZE(out_);
                            break;
                        }
                    case OP.Variable: // out2-prerelease
                        {
                            // Opcode: Variable P1 P2 * P4 *
                            //
                            // Transfer the values of bound parameter P1 into register P2
                            //
                            // If the parameter is named, then its name appears in P4 and P3==1. The P4 value is used by sqlite3_bind_parameter_name().
                            Debug.Assert(op.P1 >= 0 && op.P1 <= Vars.length);
                            Debug.Assert(op.P4.Z == null || op.P4.Z == p.VarNames[op.P1 - 1]);
                            Mem var = Vars[op.P1 - 1]; // Value being transferred
                            if (MemTooBig(var))
                                goto too_big;
                            MemShallowCopy(out_, var, MEM.Static);
                            UPDATE_MAX_BLOBSIZE(out_);
                            break;
                        }
                    // Opcode: Move P1 P2 P3 * *
                    //
                    // Move the values in register P1..P1+P3 over into registers P2..P2+P3.  Registers P1..P1+P3 are
                    // left holding a NULL.  It is an error for register ranges P1..P1+P3 and P2..P2+P3 to overlap.
                    case OP.Move:
                        {
                            int n = op.P3; // Number of registers left to copy
                            int p1 = op.P1; // Register to copy from
                            int p2 = op.P2; // Register to copy to
                            Debug.Assert(n > 0 && p1 > 0 && p2 > 0);
                            Debug.Assert(p1 + n <= p2 || p2 + n <= p1);

                            in1 = mems[op.P1];
                            out_ = mems[op.P2];
                            while (n-- != 0)
                            {
                                in1 = mems[p1 + op.P3 - n - 1];
                                out_ = mems[p2];
                                //Debug.Assert(out_ <= mems[Mems.length]);
                                //Debug.Assert(in1 <= mems[Mems.length]);
                                Debug.Assert(E.MemIsValid(in1));
                                MemAboutToChange(this, out_);
                                //byte[] malloc = out_.Malloc; // Holding variable for allocated memory
                                //out_.Malloc = null;
                                MemMove(out_, in1);
#if DEBUG
                                //if (out_.ScopyFrom >= mems[p1] && out_.ScopyFrom < mems[p1 + op.P3])
                                //    out_.ScopyFrom += p1 - op.P2;
#endif
                                //in1.Malloc = malloc;
                                REGISTER_TRACE(p2++, out_);
                            }
                            break;
                        }
                    case OP.Copy:
                        {
                            // Opcode: Copy P1 P2 P3 * *
                            //
                            // Make a copy of registers P1..P1+P3 into registers P2..P2+P3.
                            //
                            // This instruction makes a deep copy of the value.  A duplicate is made of any string or blob constant.  See also OP_SCopy.
                            int n = op.P3;
                            in1 = mems[op.P1];
                            out_ = mems[op.P2];
                            Debug.Assert(out_ != in1);
                            int x = 0; // C#
                            while (true)
                            {
                                in1 = mems[op.P1 + x];
                                out_ = mems[op.P2 + x];
                                MemShallowCopy(out_, in1, MEM.Ephem);
                                Deephemeralize(out_);
#if DEBUG
                                out_.ScopyFrom = null;
#endif
                                REGISTER_TRACE(op.P2 + op.P3 - n, out_);
                                if ((n--) == 0) break;
                                x++; // C#
                            }
                            break;
                        }
                    case OP.SCopy:  // in1, out2
                        {
                            // Opcode: SCopy P1 P2 * * *
                            //
                            // Make a shallow copy of register P1 into register P2.
                            //
                            // This instruction makes a shallow copy of the value.  If the value is a string or blob, then the copy is only a pointer to the
                            // original and hence if the original changes so will the copy. Worse, if the original is deallocated, the copy becomes invalid.
                            // Thus the program must guarantee that the original will not change during the lifetime of the copy.  Use OP_Copy to make a complete copy.
                            in1 = mems[op.P1];
                            out_ = mems[op.P2];
                            Debug.Assert(out_ != in1);
                            MemShallowCopy(out_, in1, MEM.Ephem);
#if DEBUG
                            if (out_.ScopyFrom == null) out_.ScopyFrom = in1;
#endif
                            REGISTER_TRACE(op.P2, out_);
                            break;
                        }
                    case OP.ResultRow:
                        {
                            // Opcode: ResultRow P1 P2 * * *
                            //
                            // The registers P1 through P1+P2-1 contain a single row of results. This opcode causes the sqlite3_step() call to terminate
                            // with an SQLITE_ROW return code and it sets up the sqlite3_stmt structure to provide access to the top P1 values as the result row.
                            Debug.Assert(ResColumns == op.P2);
                            Debug.Assert(op.P1 > 0);
                            Debug.Assert(op.P1 + op.P2 <= Mems.length + 1);

                            // If this statement has violated immediate foreign key constraints, do not return the number of rows modified. And do not RELEASE the statement
                            // transaction. It needs to be rolled back.
                            if ((rc = CheckFk(false)) != RC.OK)
                            {
                                Debug.Assert((ctx.Flags & Context.FLAG.CountRows) != 0);
                                Debug.Assert(UsesStmtJournal);
                                break;
                            }

                            // If the SQLITE_CountRows flag is set in sqlite3.flags mask, then DML statements invoke this opcode to return the number of rows 
                            // modified to the user. This is the only way that a VM that opens a statement transaction may invoke this opcode.
                            //
                            // In case this is such a statement, close any statement transaction opened by this VM before returning control to the user. This is to
                            // ensure that statement-transactions are always nested, not overlapping. If the open statement-transaction is not closed here, then the user
                            // may step another VM that opens its own statement transaction. This may lead to overlapping statement transactions.
                            //
                            // The statement transaction is never a top-level transaction.  Hence the RELEASE call below can never fail.
                            Debug.Assert(StatementID == 0 || (ctx.Flags & Context.FLAG.CountRows) != 0);
                            rc = CloseStatement(IPager.SAVEPOINT.RELEASE);
                            if (C._NEVER(rc != RC.OK))
                                break;

                            // Invalidate all ephemeral cursor row caches
                            CacheCtr = (CacheCtr + 2) | 1;

                            // Make sure the results of the current row are \000 terminated and have an assigned type.  The results are de-ephemeralized as a side effect.
                            //Mem[] mems2 = ResultSet = mems[op.P1];
                            ResultSet = new Mem[op.P2];
                            for (int i = 0; i < op.P2; i++)
                            {
                                ResultSet[i] = mems[op.P1 + i];
                                Debug.Assert(E.MemIsValid(ResultSet[i]));
                                Deephemeralize(ResultSet[i]);
                                Debug.Assert((ResultSet[i].Flags & MEM.Ephem) == 0 || (ResultSet[i].Flags & (MEM.Str | MEM.Blob)) == 0);
                                MemNulTerminate(ResultSet[i]);
                                MemStoreType(ResultSet[i]);
                                REGISTER_TRACE(op.P1 + i, ResultSet[i]);
                            }
                            if (ctx.MallocFailed) goto no_mem;

                            // Return SQLITE_ROW
                            PC = pc + 1;
                            rc = RC.ROW;
                            goto vdbe_return;
                        }
                    case OP.Concat: // same as TK_CONCAT, in1, in2, out3
                        {
                            // Opcode: Concat P1 P2 P3 * *
                            //
                            // Add the text in register P1 onto the end of the text in register P2 and store the result in register P3.
                            // If either the P1 or P2 text are NULL then store NULL in P3.
                            //
                            //   P3 = P2 || P1
                            //
                            // It is illegal for P1 and P3 to be the same register. Sometimes, if P3 is the same register as P2, the implementation is able to avoid a memcpy().
                            in1 = mems[op.P1];
                            in2 = mems[op.P2];
                            out_ = mems[op.P3];
                            Debug.Assert(in1 != out_);
                            if (((in1.Flags | in2.Flags) & MEM.Null) != 0)
                            {
                                MemSetNull(out_);
                                break;
                            }
                            if (E.ExpandBlob(in1) != 0 || E.ExpandBlob(in2) != 0) goto no_mem;
                            if (((in1.Flags & (MEM.Str | MEM.Blob)) == 0) && MemStringify(in1, encoding) != 0) goto no_mem; // Stringify(in1, encoding);
                            if (((in2.Flags & (MEM.Str | MEM.Blob)) == 0) && MemStringify(in2, encoding) != 0) goto no_mem; // Stringify(in2, encoding);
                            long bytes = in1.N + in2.N;
                            if (bytes > ctx.Limits[(int)LIMIT.LENGTH])
                                goto too_big;
                            E.MemSetTypeFlag(out_, MEM.Str);
                            //:if (MemGrow(out_, (int)bytes + 2, out_ == in2))
                            //:    goto no_mem;
                            //:if (out_ != in2)
                            //:    _memcpy(out_.Z, in2.Z, in2.N);
                            //:_memcpy(out_.Z[in2.N], in1.Z, in1.N);
                            if (in2.Z != null && in2.Z.Length >= in2.N)
                                if (in1.Z != null)
                                    out_.Z = in2.Z.Substring(0, in2.N) + (in1.N < in1.Z.Length ? in1.Z.Substring(0, in1.N) : in1.Z);
                                else
                                {
                                    if ((in1.Flags & MEM.Blob) == 0) // String as Blob
                                    {
                                        StringBuilder sb = new StringBuilder(in1.N);
                                        for (int i = 0; i < in1.N; i++)
                                            sb.Append((byte)in1.Z_[i]);
                                        out_.Z = in2.Z.Substring(0, in2.N) + sb.ToString();
                                    }
                                    else // UTF-8 Blob
                                        out_.Z = in2.Z.Substring(0, in2.N) + Encoding.UTF8.GetString(in1.Z_, 0, in1.Z_.Length);
                                }
                            else
                            {
                                out_.Z_ = C._alloc(in1.N + in2.N);
                                Buffer.BlockCopy(in2.Z_, 0, out_.Z_, 0, in2.N);
                                if (in1.Z_ != null)
                                    Buffer.BlockCopy(in1.Z_, 0, out_.Z_, in2.N, in1.N);
                                else
                                    for (int i = 0; i < in1.N; i++)
                                        out_.Z_[in2.N + i] = (byte)in1.Z[i];
                            }
                            //out_.Z[byte] = 0;
                            //out_.Z[byte + 1] = 0;
                            out_.Flags |= MEM.Term;
                            out_.N = (int)bytes;
                            out_.Encode = encoding;
                            UPDATE_MAX_BLOBSIZE(out_);
                            break;
                        }
                    case OP.Add: // same as TK_PLUS, in1, in2, ref3
                    case OP.Subtract: // same as TK_MINUS, in1, in2, ref3
                    case OP.Multiply: // same as TK_STAR, in1, in2, ref3
                    case OP.Divide: // same as TK_SLASH, in1, in2, ref3
                    case OP.Remainder: // same as TK_REM, in1, in2, ref3
                        {
                            // Opcode: Add P1 P2 P3 * *
                            //
                            // Add the value in register P1 to the value in register P2 and store the result in register P3.
                            // If either input is NULL, the result is NULL.
                            //
                            // Opcode: Multiply P1 P2 P3 * *
                            //
                            //
                            // Multiply the value in register P1 by the value in register P2 and store the result in register P3.
                            // If either input is NULL, the result is NULL.
                            //
                            // Opcode: Subtract P1 P2 P3 * *
                            //
                            // Subtract the value in register P1 from the value in register P2 and store the result in register P3.
                            // If either input is NULL, the result is NULL.
                            //
                            // Opcode: Divide P1 P2 P3 * *
                            //
                            // Divide the value in register P1 by the value in register P2 and store the result in register P3 (P3=P2/P1). If the value in 
                            // register P1 is zero, then the result is NULL. If either input is NULL, the result is NULL.
                            //
                            // Opcode: Remainder P1 P2 P3 * *
                            //
                            // Compute the remainder after integer division of the value in register P1 by the value in register P2 and store the result in P3.
                            // If the value in register P2 is zero the result is NULL. If either operand is NULL, the result is NULL.
                            bool intint; // Started out as two integer operands
                            long iA; // Integer value of left operand
                            long iB = 0; // Integer value of right operand
                            double rA; // Real value of left operand
                            double rB; // Real value of right operand
                            in1 = mems[op.P1];
                            ApplyNumericAffinity(in1);
                            in2 = mems[op.P2];
                            ApplyNumericAffinity(in2);
                            out_ = mems[op.P3];
                            MEM flags = (in1.Flags | in2.Flags); // Combined MEM_* flags from both inputs
                            if ((flags & MEM.Null) != 0) goto arithmetic_result_is_null;
                            bool fp_math = false;
                            if ((in1.Flags & in2.Flags & MEM.Int) == MEM.Int)
                            {
                                iA = in1.u.I;
                                iB = in2.u.I;
                                intint = true;
                                switch (op.Opcode)
                                {
                                    case OP.Add: if (MathEx.Add(ref iB, iA)) fp_math = true; break; // goto fp_math
                                    case OP.Subtract: if (MathEx.Sub(ref iB, iA)) fp_math = true; break; // goto fp_math
                                    case OP.Multiply: if (MathEx.Mul(ref iB, iA)) fp_math = true; break; // goto fp_math
                                    case OP.Divide:
                                        {
                                            if (iA == 0) goto arithmetic_result_is_null;
                                            if (iA == -1 && iB == long.MinValue) { fp_math = true; break; } // goto fp_math
                                            iB /= iA;
                                            break;
                                        }
                                    default:
                                        {
                                            if (iA == 0) goto arithmetic_result_is_null;
                                            if (iA == -1) iA = 1;
                                            iB %= iA;
                                            break;
                                        }
                                }
                            }
                            if (!fp_math)
                            {
                                out_.u.I = iB;
                                E.MemSetTypeFlag(out_, MEM.Int);
                            }
                            else
                            {
                                //fp_math:
                                rA = Vdbe.RealValue(in1);
                                rB = Vdbe.RealValue(in2);
                                switch (op.Opcode)
                                {
                                    case OP.Add: rB += rA; break;
                                    case OP.Subtract: rB -= rA; break;
                                    case OP.Multiply: rB *= rA; break;
                                    case OP.Divide:
                                        {
                                            // (double)0 In case of SQLITE_OMIT_FLOATING_POINT...
                                            if (rA == (double)0) goto arithmetic_result_is_null;
                                            rB /= rA;
                                            break;
                                        }
                                    default:
                                        {
                                            iA = (long)rA;
                                            iB = (long)rB;
                                            if (iA == 0) goto arithmetic_result_is_null;
                                            if (iA == -1) iA = 1;
                                            rB = (double)(iB % iA);
                                            break;
                                        }
                                }
#if OMIT_FLOATING_POINT
                                out_->u.I = rB;
                                MemSetTypeFlag(out_, MEM.Int);
#else
                                if (double.IsNaN(rB))
                                    goto arithmetic_result_is_null;
                                out_.R = rB;
                                E.MemSetTypeFlag(out_, MEM.Real);
                                if ((flags & MEM.Real) == 0)
                                    IntegerAffinity(out_);
#endif
                            }
                            break;
                        arithmetic_result_is_null:
                            MemSetNull(out_);
                            break;
                        }
                    case OP.CollSeq:
                        {
                            // Opcode: CollSeq P1 * * P4
                            //
                            // P4 is a pointer to a CollSeq struct. If the next call to a user function or aggregate calls sqlite3GetFuncCollSeq(), this collation sequence will
                            // be returned. This is used by the built-in min(), max() and nullif() functions.
                            //
                            // If P1 is not zero, then it is a register that a subsequent min() or max() aggregate will set to 1 if the current row is not the minimum or
                            // maximum.  The P1 register is initialized to 0 by this instruction.
                            //
                            // The interface used by the implementation of the aforementioned functions to retrieve the collation sequence set by this opcode is not available
                            // publicly, only to user functions defined in func.c.
                            Debug.Assert(op.P4Type == Vdbe.P4T.COLLSEQ);
                            if (op.P1 != 0)
                                MemSetInt64(mems[op.P1], 0);
                            break;
                        }
                    case OP.Function:
                        {
                            // Opcode: Function P1 P2 P3 P4 P5
                            //
                            // Invoke a user function (P4 is a pointer to a Function structure that defines the function) with P5 arguments taken from register P2 and
                            // successors.  The result of the function is stored in register P3. Register P3 must not be one of the function inputs.
                            //
                            // P1 is a 32-bit bitmask indicating whether or not each argument to the function was determined to be constant at compile time. If the first
                            // argument was constant then bit 0 of P1 is set. This is used to determine whether meta data associated with a user function argument using the
                            // sqlite3_set_auxdata() API may be safely retained until the next invocation of this opcode.
                            //
                            // See also: AggStep and AggFinal
                            int n = op.P5;

                            Mem[] vals = Args;
                            Debug.Assert(vals != null || n == 0);
                            Debug.Assert(op.P3 > 0 && op.P3 <= Mems.length);
                            out_ = mems[op.P3];
                            MemAboutToChange(this, out_);

                            Debug.Assert(n == 0 || (op.P2 > 0 && op.P2 + n <= Mems.length + 1));
                            Debug.Assert(op.P3 < op.P2 || op.P3 >= op.P2 + n);
                            Mem arg;
                            for (int i = 0; i < n; i++)
                            {
                                arg = mems[op.P2 + i];
                                Debug.Assert(E.MemIsValid(arg));
                                vals[i] = arg;
                                Deephemeralize(arg);
                                MemStoreType(arg);
                                REGISTER_TRACE(op.P2 + i, arg);
                            }

                            Debug.Assert(op.P4Type == Vdbe.P4T.FUNCDEF || op.P4Type == Vdbe.P4T.VDBEFUNC);
                            FuncContext fctx = new FuncContext();
                            if (op.P4Type == Vdbe.P4T.FUNCDEF)
                            {
                                fctx.Func = op.P4.Func;
                                fctx.VdbeFunc = null;
                            }
                            else
                            {
                                fctx.VdbeFunc = (VdbeFunc)op.P4.VdbeFunc;
                                fctx.Func = fctx.VdbeFunc.Func;
                            }

                            fctx.S.Flags = MEM.Null;
                            fctx.S.Ctx = ctx;
                            fctx.S.Del = null;
                            //: fctx.S.Malloc = null;

                            // The output cell may already have a buffer allocated. Move the pointer to fctx.s so in case the user-function can use
                            // the already allocated buffer instead of allocating a new one.
                            MemMove(fctx.S, out_);
                            E.MemSetTypeFlag(fctx.S, MEM.Null);

                            fctx.IsError = (RC)0;
                            if ((fctx.Func.Flags & FUNC.NEEDCOLL) != 0)
                            {
                                //Debug.Assert(op > ops);
                                Debug.Assert(ops[pc - 1].P4Type == Vdbe.P4T.COLLSEQ);
                                Debug.Assert(ops[pc - 1].Opcode == OP.CollSeq);
                                fctx.Coll = Ops[pc - 1].P4.Coll;
                            }
                            ctx.LastRowID = lastRowid;
                            fctx.Func.Func(fctx, n, vals); // IMP: R-24505-23230
                            lastRowid = ctx.LastRowID;

                            // If any auxiliary data functions have been called by this user function, immediately call the destructor for any non-static values.
                            if (fctx.VdbeFunc != null)
                            {
                                DeleteAuxData(fctx.VdbeFunc, op.P1);
                                op.P4.VdbeFunc = fctx.VdbeFunc;
                                op.P4Type = Vdbe.P4T.VDBEFUNC;
                            }

                            if (ctx.MallocFailed)
                            {
                                // Even though a malloc() has failed, the implementation of the user function may have called an sqlite3_result_XXX() function
                                // to return a value. The following call releases any resources associated with such a value.
                                MemRelease(fctx.S);
                                goto no_mem;
                            }

                            // If the function returned an error, throw an exception
                            if (fctx.IsError != 0)
                            {
                                C._setstring(ref ErrMsg, ctx, Vdbe.Value_Text(fctx.S));
                                rc = fctx.IsError;
                            }

                            // Copy the result of the function into register P3
                            ChangeEncoding(fctx.S, encoding);
                            MemMove(out_, fctx.S);
                            if (MemTooBig(out_))
                                goto too_big;
#if false
                            // The app-defined function has done something that as caused this statement to expire.  (Perhaps the function called sqlite3_exec()
                            // with a CREATE TABLE statement.)
                            if (Expired) rc = RC.ABORT;
#endif
                            REGISTER_TRACE(op.P3, out_);
                            UPDATE_MAX_BLOBSIZE(out_);
                            break;
                        }


                    case OP.BitAnd: // same as TK_BITAND, in1, in2, ref3
                    case OP.BitOr: // same as TK_BITOR, in1, in2, ref3
                    case OP.ShiftLeft: // same as TK_LSHIFT, in1, in2, ref3
                    case OP.ShiftRight: // same as TK_RSHIFT, in1, in2, ref3
                        {
                            // Opcode: BitAnd P1 P2 P3 * *
                            //
                            // Take the bit-wise AND of the values in register P1 and P2 and store the result in register P3.
                            // If either input is NULL, the result is NULL.
                            //
                            // Opcode: BitOr P1 P2 P3 * *
                            //
                            // Take the bit-wise OR of the values in register P1 and P2 and store the result in register P3.
                            // If either input is NULL, the result is NULL.
                            //
                            // Opcode: ShiftLeft P1 P2 P3 * *
                            //
                            // Shift the integer value in register P2 to the left by the number of bits specified by the integer in register P1.
                            // Store the result in register P3. If either input is NULL, the result is NULL.
                            //
                            // Opcode: ShiftRight P1 P2 P3 * *
                            //
                            // Shift the integer value in register P2 to the right by the number of bits specified by the integer in register P1.
                            // Store the result in register P3. If either input is NULL, the result is NULL.
                            in1 = mems[op.P1];
                            in2 = mems[op.P2];
                            out_ = mems[op.P3];
                            if (((in1.Flags | in2.Flags) & MEM.Null) != 0)
                            {
                                MemSetNull(out_);
                                break;
                            }
                            long iA = IntValue(in2);
                            long iB = IntValue(in1);
                            OP op2 = op.Opcode;
                            if (op2 == OP.BitAnd)
                                iA &= iB;
                            else if (op2 == OP.BitOr)
                                iA |= iB;
                            else if (iB != 0)
                            {
                                Debug.Assert(op2 == OP.ShiftRight || op2 == OP.ShiftLeft);

                                // If shifting by a negative amount, shift in the other direction
                                if (iB < 0)
                                {
                                    Debug.Assert(OP.ShiftRight == OP.ShiftLeft + 1);
                                    op2 = (OP)(2 * (int)OP.ShiftLeft + 1 - op2);
                                    iB = (iB > -64 ? -iB : 64);
                                }

                                if (iB >= 64)
                                    iA = (iA >= 0 || op2 == OP.ShiftLeft ? 0 : -1);
                                else
                                {
                                    ulong uA;
                                    if (op2 == OP.ShiftLeft)
                                        iA = iA << (int)iB; //: uA = (ulong)(iA << 0); //: memcpy(uA, iA, sizeof(uA));
                                    else
                                    {
                                        iA = iA >> (int)iB; //: uA = (ulong)(iA << 0); //: memcpy(uA, iA, sizeof(uA));
                                        // Sign-extend on a right shift of a negative number
                                        //:if (iA < 0) uA |= (((0xffffffff) << (byte)32) | 0xffffffff) << (byte)(64 - iB);
                                    }
                                    //: iA = (long)(uA << 0); //: memcpy(iA, uA, sizeof(iA));
                                }
                            }
                            out_.u.I = iA;
                            E.MemSetTypeFlag(out_, MEM.Int);
                            break;
                        }
                    case OP.AddImm: // in1
                        {
                            // Opcode: AddImm  P1 P2 * * *
                            //
                            // Add the constant P2 to the value in register P1. The result is always an integer.
                            //
                            // To force any register to be an integer, just add 0.
                            in1 = mems[op.P1];
                            MemAboutToChange(this, in1);
                            MemIntegerify(in1);
                            in1.u.I += op.P2;
                            break;
                        }
                    case OP.MustBeInt: // jump, in1
                        {
                            // Opcode: MustBeInt P1 P2 * * *
                            // 
                            // Force the value in register P1 to be an integer.  If the value in P1 is not an integer and cannot be converted into an integer
                            // without data loss, then jump immediately to P2, or if P2==0 raise an SQLITE_MISMATCH exception.
                            in1 = mems[op.P1];
                            ApplyAffinity(in1, AFF.NUMERIC, encoding);
                            if ((in1.Flags & MEM.Int) == 0)
                            {
                                if (op.P2 == 0)
                                {
                                    rc = RC.MISMATCH;
                                    goto abort_due_to_error;
                                }
                                else
                                    pc = op.P2 - 1;
                            }
                            else
                                E.MemSetTypeFlag(in1, MEM.Int);
                            break;
                        }
#if !OMIT_FLOATING_POINT
                    case OP.RealAffinity: // in1
                        {
                            // Opcode: RealAffinity P1 * * * *
                            //
                            // If register P1 holds an integer convert it to a real value.
                            //
                            // This opcode is used when extracting information from a column that has REAL affinity.  Such column values may still be stored as
                            // integers, for space efficiency, but after extraction we want them to have only a real value.
                            in1 = mems[op.P1];
                            if ((in1.Flags & MEM.Int) != 0)
                                MemRealify(in1);
                            break;
                        }
#endif
#if !OMIT_CAST
                    case OP.ToText: // same as TK_TO_TEXT, in1
                        {
                            // Opcode: ToText P1 * * * *
                            //
                            // Force the value in register P1 to be text. If the value is numeric, convert it to a string using the
                            // equivalent of printf().  Blob values are unchanged and are afterwards simply interpreted as text.
                            //
                            // A NULL value is not changed by this routine.  It remains NULL.
                            in1 = mems[op.P1];
                            MemAboutToChange(this, in1);
                            if ((in1.Flags & MEM.Null) != 0) break;
                            Debug.Assert(MEM.Str == (MEM)((int)MEM.Blob >> 3));
                            in1.Flags |= (MEM)((int)(in1.Flags & MEM.Blob) >> 3);
                            ApplyAffinity(in1, AFF.TEXT, encoding);
                            rc = E.ExpandBlob(in1);
                            Debug.Assert((in1.Flags & MEM.Str) != 0 || ctx.MallocFailed);
                            in1.Flags &= ~(MEM.Int | MEM.Real | MEM.Blob | MEM.Zero);
                            UPDATE_MAX_BLOBSIZE(in1);
                            break;
                        }
                    case OP.ToBlob: // same as TK_TO_BLOB, in1
                        {
                            // Opcode: ToBlob P1 * * * *
                            //
                            // Force the value in register P1 to be a BLOB. If the value is numeric, convert it to a string first.
                            // Strings are simply reinterpreted as blobs with no change to the underlying data.
                            //
                            // A NULL value is not changed by this routine.  It remains NULL.
                            in1 = mems[op.P1];
                            if ((in1.Flags & MEM.Null) != 0) break;
                            if ((in1.Flags & MEM.Blob) == 0)
                            {
                                ApplyAffinity(in1, AFF.TEXT, encoding);
                                Debug.Assert((in1.Flags & MEM.Str) != 0 || ctx.MallocFailed);
                                E.MemSetTypeFlag(in1, MEM.Blob);
                            }
                            else
                                in1.Flags &= ~(MEM.TypeMask & ~MEM.Blob);
                            UPDATE_MAX_BLOBSIZE(in1);
                            break;
                        }
                    case OP.ToNumeric: // same as TK_TO_NUMERIC, in1
                        {
                            // Opcode: ToNumeric P1 * * * *
                            //
                            // Force the value in register P1 to be numeric (either an integer or a floating-point number.)
                            // If the value is text or blob, try to convert it to an using the equivalent of atoi() or atof() and store 0 if no such conversion is possible.
                            //
                            // A NULL value is not changed by this routine.  It remains NULL.
                            in1 = mems[op.P1];
                            MemNumerify(in1);
                            break;
                        }
#endif
                    case OP.ToInt:// same as TK_TO_INT, in1
                        {
                            // Opcode: ToInt P1 * * * *
                            //
                            // Force the value in register P1 to be an integer.  If The value is currently a real number, drop its fractional part.
                            // If the value is text or blob, try to convert it to an integer using the equivalent of atoi() and store 0 if no such conversion is possible.
                            //
                            // A NULL value is not changed by this routine.  It remains NULL.
                            in1 = mems[op.P1];
                            if ((in1.Flags & MEM.Null) == 0)
                                MemIntegerify(in1);
                            break;
                        }
#if !OMIT_CAST && !OMIT_FLOATING_POINT
                    case OP.ToReal: // same as TK_TO_REAL, in1
                        {
                            // Opcode: ToReal P1 * * * *
                            //
                            // Force the value in register P1 to be a floating point number. If The value is currently an integer, convert it.
                            // If the value is text or blob, try to convert it to an integer using the equivalent of atoi() and store 0.0 if no such conversion is possible.
                            //
                            // A NULL value is not changed by this routine.  It remains NULL.
                            in1 = mems[op.P1];
                            MemAboutToChange(this, in1);
                            if ((in1.Flags & MEM.Null) == 0)
                                MemRealify(in1);
                            break;
                        }
#endif
                    case OP.Eq: // same as TK_EQ, jump, in1, in3
                    case OP.Ne: // same as TK_NE, jump, in1, in3
                    case OP.Lt: // same as TK_LT, jump, in1, in3
                    case OP.Le: // same as TK_LE, jump, in1, in3
                    case OP.Gt: // same as TK_GT, jump, in1, in3
                    case OP.Ge: // same as TK_GE, jump, in1, in3
                        {
                            // Opcode: Lt P1 P2 P3 P4 P5
                            //
                            // Compare the values in register P1 and P3.  If reg(P3)<reg(P1) then jump to address P2.  
                            //
                            // If the SQLITE_JUMPIFNULL bit of P5 is set and either reg(P1) or reg(P3) is NULL then take the jump.  If the SQLITE_JUMPIFNULL 
                            // bit is clear then fall through if either operand is NULL.
                            //
                            // The SQLITE_AFF_MASK portion of P5 must be an affinity character - SQLITE_AFF_TEXT, SQLITE_AFF_INTEGER, and so forth. An attempt is made 
                            // to coerce both inputs according to this affinity before the comparison is made. If the SQLITE_AFF_MASK is 0x00, then numeric
                            // affinity is used. Note that the affinity conversions are stored back into the input registers P1 and P3.  So this opcode can cause
                            // persistent changes to registers P1 and P3.
                            //
                            // Once any conversions have taken place, and neither value is NULL, the values are compared. If both values are blobs then memcmp() is
                            // used to determine the results of the comparison.  If both values are text, then the appropriate collating function specified in
                            // P4 is  used to do the comparison.  If P4 is not specified then memcmp() is used to compare text string.  If both values are
                            // numeric, then a numeric comparison is used. If the two values are of different types, then numbers are considered less than
                            // strings and strings are considered less than blobs.
                            //
                            // If the SQLITE_STOREP2 bit of P5 is set, then do not jump.  Instead, store a boolean result (either 0, or 1, or NULL) in register P2.
                            //
                            // If the SQLITE_NULLEQ bit is set in P5, then NULL values are considered equal to one another, provided that they do not have their MEM_Cleared
                            // bit set.
                            //
                            // Opcode: Ne P1 P2 P3 P4 P5
                            //
                            // This works just like the Lt opcode except that the jump is taken if the operands in registers P1 and P3 are not equal.  See the Lt opcode for
                            // additional information.
                            //
                            // If SQLITE_NULLEQ is set in P5 then the result of comparison is always either true or false and is never NULL.  If both operands are NULL then the result
                            // of comparison is false.  If either operand is NULL then the result is true. If neither operand is NULL the result is the same as it would be if
                            // the SQLITE_NULLEQ flag were omitted from P5.
                            //
                            // Opcode: Eq P1 P2 P3 P4 P5
                            //
                            // This works just like the Lt opcode except that the jump is taken if the operands in registers P1 and P3 are equal.
                            // See the Lt opcode for additional information.
                            //
                            // If SQLITE_NULLEQ is set in P5 then the result of comparison is always either true or false and is never NULL.  If both operands are NULL then the result
                            // of comparison is true.  If either operand is NULL then the result is false. If neither operand is NULL the result is the same as it would be if
                            // the SQLITE_NULLEQ flag were omitted from P5.
                            //
                            // Opcode: Le P1 P2 P3 P4 P5
                            //
                            // This works just like the Lt opcode except that the jump is taken if the content of register P3 is less than or equal to the content of
                            // register P1.  See the Lt opcode for additional information.
                            //
                            // Opcode: Gt P1 P2 P3 P4 P5
                            //
                            // This works just like the Lt opcode except that the jump is taken if the content of register P3 is greater than the content of
                            // register P1.  See the Lt opcode for additional information.
                            //
                            // Opcode: Ge P1 P2 P3 P4 P5
                            //
                            // This works just like the Lt opcode except that the jump is taken if the content of register P3 is greater than or equal to the content of
                            // register P1.  See the Lt opcode for additional information.
                            in1 = mems[op.P1];
                            in3 = mems[op.P3];
                            MEM flags1 = in1.Flags; // Copy of initial value of in1->flags
                            MEM flags3 = in3.Flags; // Copy of initial value of in3->flags
                            int res = 0; // Result of the comparison of in1 against in3
                            if (((flags1 | flags3) & MEM.Null) != 0)
                            {
                                // One or both operands are NULL
                                if (((AFF)op.P5 & AFF.BIT_NULLEQ) != 0)
                                {
                                    // If SQLITE_NULLEQ is set (which will only happen if the operator is OP_Eq or OP_Ne) then take the jump or not depending on whether or not both operands are null.
                                    Debug.Assert(op.Opcode == OP.Eq || op.Opcode == OP.Ne);
                                    Debug.Assert((flags1 & MEM.Cleared) == 0);
                                    res = ((flags1 & flags3 & MEM.Null) == 0 ? 1 : 0); // Results are equal/not equal
                                }
                                else
                                {
                                    // SQLITE_NULLEQ is clear and at least one operand is NULL, then the result is always NULL. The jump is taken if the SQLITE_JUMPIFNULL bit is set.
                                    if (((AFF)op.P5 & AFF.BIT_STOREP2) != 0)
                                    {
                                        out_ = mems[op.P2];
                                        E.MemSetTypeFlag(out_, MEM.Null);
                                        REGISTER_TRACE(this, op.P2, out_);
                                    }
                                    else if (((AFF)op.P5 & AFF.BIT_JUMPIFNULL) != 0)
                                        pc = op.P2 - 1;
                                    break;
                                }
                            }
                            else
                            {
                                // Neither operand is NULL.  Do a comparison.
                                AFF affinity = ((AFF)op.P5 & AFF.MASK); // Affinity to use for comparison
                                if (affinity != 0)
                                {
                                    ApplyAffinity(in1, affinity, encoding);
                                    ApplyAffinity(in3, affinity, encoding);
                                    if (ctx.MallocFailed) goto no_mem;
                                }

                                Debug.Assert(op.P4Type == Vdbe.P4T.COLLSEQ || op.P4.Coll == null);
                                E.ExpandBlob(in1);
                                E.ExpandBlob(in3);
                                res = MemCompare(in3, in1, op.P4.Coll);
                            }
                            switch (op.Opcode)
                            {
                                case OP.Eq: res = (res == 0 ? 1 : 0); break;
                                case OP.Ne: res = (res != 0 ? 1 : 0); break;
                                case OP.Lt: res = (res < 0 ? 1 : 0); break;
                                case OP.Le: res = (res <= 0 ? 1 : 0); break;
                                case OP.Gt: res = (res > 0 ? 1 : 0); break;
                                default: res = (res >= 0 ? 1 : 0); break;
                            }

                            if (((AFF)op.P5 & AFF.BIT_STOREP2) != 0)
                            {
                                out_ = mems[op.P2];
                                MemAboutToChange(this, out_);
                                E.MemSetTypeFlag(out_, MEM.Int);
                                out_.u.I = res;
                                REGISTER_TRACE(p, op.P2, out_);
                            }
                            else if (res != 0)
                                pc = op.P2 - 1;

                            // Undo any changes made by applyAffinity() to the input registers.
                            in1.Flags = (in1.Flags & ~MEM.TypeMask) | (flags1 & MEM.TypeMask);
                            in3.Flags = (in3.Flags & ~MEM.TypeMask) | (flags3 & MEM.TypeMask);
                            break;
                        }
                    case OP.Permutation:
                        {
                            // Opcode: Permutation * * * P4 *
                            //
                            // Set the permutation used by the OP_Compare operator to be the array of integers in P4.
                            //
                            // The permutation is only valid until the next OP_Compare that has the OPFLAG_PERMUTE bit set in P5. Typically the OP_Permutation should 
                            // occur immediately prior to the OP_Compare.
                            Debug.Assert(op.P4Type == Vdbe.P4T.INTARRAY);
                            Debug.Assert(op.P4.Is != null);
                            permutes = op.P4.Is;
                            break;
                        }
                    case OP.Compare:
                        {
                            // Opcode: Compare P1 P2 P3 P4 P5
                            //
                            // Compare two vectors of registers in reg(P1)..reg(P1+P3-1) (call this vector "A") and in reg(P2)..reg(P2+P3-1) ("B").  Save the result of
                            // the comparison for use by the next OP_Jump instruct.
                            //
                            // If P5 has the OPFLAG_PERMUTE bit set, then the order of comparison is determined by the most recent OP_Permutation operator.  If the
                            // OPFLAG_PERMUTE bit is clear, then register are compared in sequential order.
                            //
                            // P4 is a KeyInfo structure that defines collating sequences and sort orders for the comparison.  The permutation applies to registers
                            // only.  The KeyInfo elements are used sequentially.
                            //
                            // The comparison is a sort comparison, so NULLs compare equal, NULLs are less than numbers, numbers are less than strings,
                            // and strings are less than blobs.
                            if (((OPFLAG)op.P5 & OPFLAG.PERMUTE) == 0) permutes = null;
                            int n = op.P3;
                            KeyInfo keyInfo = op.P4.KeyInfo;
                            Debug.Assert(n > 0);
                            Debug.Assert(keyInfo != null);
                            int p1 = op.P1;
                            int p2 = op.P2;
#if DEBUG
                            if (permutes != null)
                            {
                                int k, max = 0;
                                for (k = 0; k < n; k++) if (permutes[k] > max) max = permutes[k];
                                Debug.Assert(p1 > 0 && p1 + max <= Mems.length + 1);
                                Debug.Assert(p2 > 0 && p2 + max <= Mems.length + 1);
                            }
                            else
                            {
                                Debug.Assert(p1 > 0 && p1 + n <= Mems.length + 1);
                                Debug.Assert(p2 > 0 && p2 + n <= Mems.length + 1);
                            }
#endif
                            for (int i = 0; i < n; i++)
                            {
                                int idx = (permutes != null ? permutes[i] : i);
                                Debug.Assert(E.MemIsValid(mems[p1 + idx]));
                                Debug.Assert(E.MemIsValid(mems[p2 + idx]));
                                REGISTER_TRACE(p1 + idx, mems[p1 + idx]);
                                REGISTER_TRACE(p2 + idx, mems[p2 + idx]);
                                Debug.Assert(i < keyInfo.Fields);
                                CollSeq coll = keyInfo.Colls[i]; // Collating sequence to use on this term
                                SO rev = keyInfo.SortOrders[i]; // True for DESCENDING sort order
                                compare = sqlite3MemCompare(mems[p1 + idx], mems[p2 + idx], coll);
                                if (compare != 0)
                                {
                                    if (rev != 0)
                                        compare = -compare;
                                    break;
                                }
                            }
                            permutes = null;
                            break;
                        }
                    case OP.Jump: // jump
                        {
                            // Opcode: Jump P1 P2 P3 * *
                            //
                            // Jump to the instruction at address P1, P2, or P3 depending on whether in the most recent OP_Compare instruction the P1 vector was less than
                            // equal to, or greater than the P2 vector, respectively.
                            if (compare < 0) pc = op.P1 - 1;
                            else if (compare == 0) pc = op.P2 - 1;
                            else pc = op.P3 - 1;
                            break;
                        }
                    case OP.And: // same as TK_AND, in1, in2, ref3
                    case OP.Or: // same as TK_OR, in1, in2, ref3
                        {
                            // Opcode: And P1 P2 P3 * *
                            //
                            // Take the logical AND of the values in registers P1 and P2 and write the result into register P3.
                            //
                            // If either P1 or P2 is 0 (false) then the result is 0 even if the other input is NULL.  A NULL and true or two NULLs give
                            // a NULL output.
                            //
                            // Opcode: Or P1 P2 P3 * *
                            //
                            // Take the logical OR of the values in register P1 and P2 and store the answer in register P3.
                            //
                            // If either P1 or P2 is nonzero (true) then the result is 1 (true) even if the other input is NULL.  A NULL and false or two NULLs
                            // give a NULL output.
                            in1 = mems[op.P1];
                            int v1 = ((in1.Flags & MEM.Null) != 0 ? 2 : (IntValue(in1) != 0 ? 1 : 0)); // Left operand:  0==FALSE, 1==TRUE, 2==UNKNOWN or NULL
                            in2 = mems[op.P2];
                            int v2 = ((in2.Flags & MEM.Null) != 0 ? 2 : (IntValue(in2) != 0 ? 1 : 0)); // Right operand: 0==FALSE, 1==TRUE, 2==UNKNOWN or NULL
                            if (op.Opcode == OP.And)
                            {
                                byte[] and_logic = new byte[] { 0, 0, 0, 0, 1, 2, 0, 2, 2 };
                                v1 = and_logic[v1 * 3 + v2];
                            }
                            else
                            {
                                byte[] or_logic = new byte[] { 0, 1, 2, 1, 1, 1, 2, 1, 2 };
                                v1 = or_logic[v1 * 3 + v2];
                            }
                            out_ = mems[op.P3];
                            if (v1 == 2)
                                E.MemSetTypeFlag(out_, MEM.Null);
                            else
                            {
                                out_.u.I = v1;
                                E.MemSetTypeFlag(out_, MEM.Int);
                            }
                            break;
                        }
                    case OP.Not: // same as TK_NOT, in1
                        {
                            // Opcode: Not P1 P2 * * *
                            //
                            // Interpret the value in register P1 as a boolean value.  Store the boolean complement in register P2.  If the value in register P1 is
                            // NULL, then a NULL is stored in P2.
                            in1 = mems[op.P1];
                            out_ = mems[op.P2];
                            if ((in1.Flags & MEM.Null) != 0)
                                MemSetNull(out_);
                            else
                                MemSetInt64(out_, IntValue(in1) == 0 ? 1 : 0);
                            break;
                        }
                    case OP.BitNot: // same as TK_BITNOT, in1
                        {
                            // Opcode: BitNot P1 P2 * * *
                            //
                            // Interpret the content of register P1 as an integer.  Store the ones-complement of the P1 value into register P2.  If P1 holds
                            // a NULL then store a NULL in P2.
                            in1 = mems[op.P1];
                            out_ = mems[op.P2];
                            if ((in1.Flags & MEM.Null) != 0)
                                MemSetNull(out_);
                            else
                                MemSetInt64(out_, ~IntValue(in1));
                            break;
                        }
                    case OP.If:
                    case OP.IfNot:
                        {
                            // Opcode: If P1 P2 P3 * *
                            //
                            // Jump to P2 if the value in register P1 is true.  The value is considered true if it is numeric and non-zero.  If the value
                            // in P1 is NULL then take the jump if P3 is non-zero.
                            //
                            // Opcode: IfNot P1 P2 P3 * *
                            //
                            // Jump to P2 if the value in register P1 is False.  The value is considered false if it has a numeric value of zero.  If the value
                            // in P1 is NULL then take the jump if P3 is zero.
                            int c;
                            in1 = mems[op.P1];
                            if ((in1.Flags & MEM.Null) != 0)
                                c = op.P3;
                            else
                            {
#if OMIT_FLOATING_POINT
                                c = (IntValue(in1) != 0 ? 1 : 0);
#else
                                c = (RealValue(in1) != 0.0 ? 1 : 0);
#endif
                                if (op.Opcode == OP.IfNot) c = !c;
                            }
                            if (c != 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.IsNull: // same as TK_ISNULL, jump, in1
                        {
                            // Opcode: IsNull P1 P2 * * *
                            //
                            // Jump to P2 if the value in register P1 is NULL.
                            in1 = mems[op.P1];
                            if ((in1.Flags & MEM.Null) != 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.NotNull: // same as TK_NOTNULL, jump, in1
                        {
                            // Opcode: NotNull P1 P2 * * *
                            //
                            // Jump to P2 if the value in register P1 is not NULL.  
                            in1 = mems[op.P1];
                            if ((in1.Flags & MEM.Null) == 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.Column:
                        {
                            // Opcode: Column P1 P2 P3 P4 P5
                            //
                            // Interpret the data that cursor P1 points to as a structure built using the MakeRecord instruction.  (See the MakeRecord opcode for additional
                            // information about the format of the data.)  Extract the P2-th column from this record.  If there are less that (P2+1) 
                            // values in the record, extract a NULL.
                            //
                            // The value extracted is stored in register P3.
                            //
                            // If the column contains fewer than P2 fields, then extract a NULL.  Or, if the P4 argument is a P4_MEM use the value of the P4 argument as
                            // the result.
                            //
                            // If the OPFLAG_CLEARCACHE bit is set on P5 and P1 is a pseudo-table cursor, then the cache of the cursor is reset prior to extracting the column.
                            // The first OP_Column against a pseudo-table after the value of the content register has changed should have this bit set.
                            //
                            // If the OPFLAG_LENGTHARG and OPFLAG_TYPEOFARG bits are set on P5 when the result is guaranteed to only be used as the argument of a length()
                            // or typeof() function, respectively.  The loading of large blobs can be skipped for length() and all content loading can be skipped for typeof().
                            int p1 = op.P1; // P1 value of the opcode
                            int p2 = op.P2; // column number to retrieve
                            Mem sMem = C._alloc(sMem); // For storing the record being decoded
                            Debug.Assert(p1 < Cursors.length);
                            Debug.Assert(op.P3 > 0 && op.P3 <= Mems.length);
                            Mem dest = mems[op.P3]; // Where to write the extracted value
                            MemAboutToChange(this, dest);

                            // This block sets the variable payloadSize to be the total number of bytes in the record.
                            //
                            // zRec is set to be the complete text of the record if it is available. The complete record text is always available for pseudo-tables
                            // If the record is stored in a cursor, the complete record text might be available in the  pC->aRow cache.  Or it might not be.
                            // If the data is unavailable,  zRec is set to NULL.
                            //
                            // We also compute the number of columns in the record.  For cursors, the number of columns is stored in the VdbeCursor.Fields element.
                            VdbeCursor c = Cursors[p1]; // The VDBE cursor
                            Debug.Assert(c != null);
#if !OMIT_VIRTUALTABLE
                            Debug.Assert(c.VtabCursor == null);
#endif

                            Btree.BtCursor crsr = c.Cursor; // The BTree cursor
                            uint payloadSize = 0; // Number of bytes in the record
                            long payloadSize64 = 0; // Number of bytes in the record
                            byte[] rec = null; // Pointer to complete record-data
                            if (crsr != null)
                            {
                                // The record is stored in a B-Tree
                                rc = CursorMoveto(c);
                                if (rc != 0) goto abort_due_to_error;
                                if (c.NullRow)
                                    payloadSize = 0;
                                else if (c.CacheStatus == CacheCtr)
                                {
                                    payloadSize = (uint)c.PayloadSize;
                                    rec = C._alloc((int)payloadSize);
                                    Buffer.BlockCopy(crsr.Info.Cell, c.Rows, rec, 0, (int)payloadSize);
                                }
                                else if (c.IsIndex)
                                {
                                    Debug.Assert(Btree.CursorIsValid(crsr));
                                    rc = Btree.KeySize(crsr, ref payloadSize64);
                                    Debug.Assert(rc == RC.OK); // True because of CursorMoveto() call above
                                    // sqlite3BtreeParseCellPtr() uses getVarint32() to extract the payload size, so it is impossible for payloadSize64 to be larger than 32 bits.
                                    Debug.Assert(((ulong)payloadSize64 & uint.MaxValue) == (ulong)payloadSize64);
                                    payloadSize = (uint)payloadSize64;
                                }
                                else
                                {
                                    Debug.Assert(Btree.CursorIsValid(crsr));
                                    rc = Btree.DataSize(crsr, ref payloadSize);
                                    Debug.Assert(rc == RC.OK); // DataSize() cannot fail
                                }
                            }
                            else if (c.PseudoTableReg > 0)
                            {
                                // The record is the sole entry of a pseudo-table
                                Mem reg = mems[c.PseudoTableReg]; // PseudoTable input register
                                if (c.MultiPseudo)
                                {
                                    MemShallowCopy(dest, reg + p2, MEM.Ephem);
                                    Deephemeralize(dest);
                                    goto op_column_out;
                                }
                                Debug.Assert((reg.Flags & MEM.Blob) != 0);
                                Debug.Assert(E.MemIsValid(reg));
                                payloadSize = (uint)reg.N;
                                rec = reg.Z_;
                                c.CacheStatus = (((OPFLAG)op.P5 & OPFLAG.CLEARCACHE) != 0 ? E.CACHE_STALE : CacheCtr);
                                Debug.Assert(payloadSize == 0 || rec != null);
                            }
                            else
                                payloadSize = 0; // Consider the row to be NULL

                            // If payloadSize is 0, then just store a NULL.  This can happen because of nullRow or because of a corrupt database.
                            if (payloadSize == 0)
                            {
                                E.MemSetTypeFlag(dest, MEM.Null);
                                goto op_column_out;
                            }
                            Debug.Assert(ctx.Limits[(int)LIMIT.LENGTH] >= 0);
                            if (payloadSize > (uint)ctx.Limits[(int)LIMIT.LENGTH])
                                goto too_big;

                            int fields = c.Fields; // number of fields in the record
                            Debug.Assert(p2 < fields);

                            // Read and parse the table header.  Store the results of the parse into the record header cache fields of the cursor.
                            uint[] types = c.Types; // aType[i] holds the numeric type of the i-th column
                            uint[] offsets; // aOffset[i] is offset to start of data for i-th column
                            byte[] data = null; // Part of the record being decoded
                            int len; // The length of the serialized data for the column
                            uint t; // A type code from the record header
                            if (c.CacheStatus == CacheCtr)
                                offsets = c.Offsets;
                            else
                            {
                                Debug.Assert(types != null);
                                int avail = 0; // Number of bytes of available data
                                //: c.Offsets = offsets = types[fields];
                                offsets = new uint[fields];
                                c.Offsets = offsets;
                                c.PayloadSize = (int)payloadSize;
                                c.CacheStatus = CacheCtr;

                                // Figure out how many bytes are in the header
                                if (rec != null)
                                    data = rec;
                                else
                                {
                                    data = (c.IsIndex ? Btree.KeyFetch(crsr, ref avail, ref c.Rows) : Btree.DataFetch(crsr, ref avail, ref c.Rows));
                                    // If KeyFetch()/DataFetch() managed to get the entire payload, save the payload in the pC->aRow cache.  That will save us from
                                    // having to make additional calls to fetch the content portion of the record.
                                    Debug.Assert(avail >= 0);
                                    if (payloadSize <= (uint)avail)
                                    {
                                        rec = data;
                                        //c.Rows = data;
                                    }
                                    else
                                        c.Rows = -1; //: c.Rows = null;
                                }
                                // The following assert is true in all cases except when the database file has been corrupted externally.
                                //Debug.Assert(rec != 0 || avail >= payloadSize || avail >= 9);
                                uint offset; // Offset into the data
                                int sizeHdr = ConvertEx.GetVarint32(data, out offset); // Size of the header size field at start of record

                                // Make sure a corrupt database has not given us an oversize header. Do this now to avoid an oversize memory allocation.
                                //
                                // Type entries can be between 1 and 5 bytes each.  But 4 and 5 byte types use so much data space that there can only be 4096 and 32 of
                                // them, respectively.  So the maximum header length results from a 3-byte type for each of the maximum of 32768 columns plus three
                                // extra bytes for the header length itself.  32768*3 + 3 = 98307.
                                if (offset > 98307)
                                {
                                    rc = SysEx.CORRUPT_BKPT();
                                    goto op_column_out;
                                }

                                // Compute in len the number of bytes of data we need to read in order to get nField type values.  offset is an upper bound on this.  But
                                // nField might be significantly less than the true number of columns in the table, and in that case, 5*nField+3 might be smaller than offset.
                                // We want to minimize len in order to limit the size of the memory allocation, especially if a corrupt database file has caused offset
                                // to be oversized. Offset is limited to 98307 above.  But 98307 might still exceed Robson memory allocation limits on some configurations.
                                // On systems that cannot tolerate large memory allocations, nField*5+3 will likely be much smaller since nField will likely be less than
                                // 20 or so.  This insures that Robson memory allocation limits are not exceeded even for corrupt database files.
                                len = fields * 5 + 3;
                                if (len > (int)offset) len = (int)offset;

                                // The KeyFetch() or DataFetch() above are fast and will get the entire record header in most cases.  But they will fail to get the complete
                                // record header if the record header does not fit on a single page in the B-Tree.  When that happens, use sqlite3VdbeMemFromBtree() to
                                // acquire the complete header text.
                                if (rec == null && avail < len)
                                {
                                    sMem.Flags = 0;
                                    sMem.Ctx = null;
                                    rc = MemFromBtree(crsr, 0, len, c.IsIndex, sMem);
                                    if (rc != RC.OK)
                                        goto op_column_out;
                                    data = sMem.Z_;
                                }
                                int endHdr = len; //: data[len]; // Pointer to first byte after the header
                                int idx = sizeHdr; //: data[sizeHdr]; // Index into header

                                // Scan the header and use it to fill in the aType[] and aOffset[] arrays.  aType[i] will contain the type integer for the i-th
                                // column and aOffset[i] will contain the offset from the beginning of the record to the start of the data for the i-th column
                                for (int i = 0; i < fields; i++)
                                {
                                    if (idx < endHdr)
                                    {
                                        offsets[i] = offset;
                                        if (data[idx] < 0x80)
                                        {
                                            t = data[idx];
                                            idx++;
                                        }
                                        else
                                            idx += ConvertEx.GetVarint32(data, idx, out t);
                                        types[i] = t;
                                        uint sizeField = SerialTypeLen(t); // Number of bytes in the content of a field
                                        offset += sizeField;
                                        if (offset < sizeField) // True if offset overflows
                                        {
                                            idx = int.MaxValue; // Forces SQLITE_CORRUPT return below
                                            break;
                                        }
                                    }
                                    else
                                        // If i is less that nField, then there are fewer fields in this record than SetNumColumns indicated there are columns in the
                                        // table. Set the offset for any extra columns not present in the record to 0. This tells code below to store the default value
                                        // for the column instead of deserializing a value from the record.
                                        offsets[i] = 0;
                                }
                                MemRelease(sMem);
                                sMem.Flags = MEM.Null;

                                // If we have read more header data than was contained in the header, or if the end of the last field appears to be past the end of the
                                // record, or if the end of the last field appears to be before the end of the record (when all fields present), then we must be dealing 
                                // with a corrupt database.
                                if ((idx > endHdr) || (offset > payloadSize) || (idx == endHdr && offset != payloadSize))
                                {
                                    rc = SysEx.CORRUPT_BKPT();
                                    goto op_column_out;
                                }
                            }

                            // Get the column information. If aOffset[p2] is non-zero, then deserialize the value from the record. If aOffset[p2] is zero,
                            // then there are not enough fields in the record to satisfy the request.  In this case, set the value NULL or to P4 if P4 is
                            // a pointer to a Mem object.
                            if (offsets[p2] != 0)
                            {
                                Debug.Assert(rc == RC.OK);
                                if (rec != null)
                                {
                                    E.VdbeMemRelease(dest);
                                    SerialGet(rec, (int)offsets[p2], types[p2], dest);
                                }
                                else
                                {
                                    // This branch happens only when the row overflows onto multiple pages
                                    t = types[p2];
                                    if (((OPFLAG)op.P5 & (OPFLAG.LENGTHARG | OPFLAG.TYPEOFARG)) != 0 && ((t >= 12 && (t & 1) == 0) || ((OPFLAG)op.P5 & OPFLAG.TYPEOFARG) != 0))
                                    {
                                        // Content is irrelevant for the typeof() function and for the length(X) function if X is a blob.  So we might as well use
                                        // bogus content rather than reading content from disk.  NULL works for text and blob and whatever is in the payloadSize64 variable
                                        // will work for everything else.
                                        data = (t < 12 ? BitConverter.GetBytes(payloadSize64) : null);
                                    }
                                    else
                                    {
                                        len = (int)SerialTypeLen(types[p2]);
                                        MemMove(sMem, dest);
                                        rc = MemFromBtree(crsr, (int)offsets[p2], len, c.IsIndex, sMem);
                                        if (rc != RC.OK)
                                            goto op_column_out;
                                        data = sMem.Z_;
                                        sMem.Z_ = null;
                                    }
                                    SerialGet(data, types[p2], dest);
                                }
                                dest.Encode = encoding;
                            }
                            else
                            {
                                if (op.P4Type == P4T.MEM)
                                    MemShallowCopy(dest, op.P4.Mem, MEM.Static);
                                else
                                    E.MemSetTypeFlag(dest, MEM.Null);
                            }

                            // If we dynamically allocated space to hold the data (in the sqlite3VdbeMemFromBtree() call above) then transfer control of that
                            // dynamically allocated space over to the pDest structure. This prevents a memory copy.
                            //: if (sMem.Malloc != null)
                            //: {
                            //:     Debug.Assert(sMem.Z == sMem.Malloc);
                            //:     Debug.Assert(sMem.Del == null);
                            //:     Debug.Assert((dest.Flags & MEM.Dyn) == 0);
                            //:     Debug.Assert((dest.Flags & (MEM.Blob | MEM.Str)) == 0 || dest.Z == sMem.Z);
                            //:     dest.Flags &= ~(MEM.Ephem | MEM.Static);
                            //:     dest.Flags |= MEM.Term;
                            //:     dest.Z = sMem.Z;
                            //:     dest.Malloc = sMem.zMalloc;
                            //: }

                            rc = MemMakeWriteable(dest);

                        op_column_out:
                            UPDATE_MAX_BLOBSIZE(dest);
                            REGISTER_TRACE(op.P3, dest);
                            break;
                        }
                    case OP.Affinity:
                        {
                            // Opcode: Affinity P1 P2 * P4 *
                            //
                            // Apply affinities to a range of P2 registers starting with P1.
                            //
                            // P4 is a string that is P2 characters long. The nth character of the string indicates the column affinity that should be used for the nth
                            // memory cell in the range.
                            string affinity = op.P4.Z; // The affinity to be applied
                            Debug.Assert(affinity != null);
                            Debug.Assert(affinity.Length <= op.P2); //: affinity[op.P2] == 0
                            //: in1 = mems[op.P1];
                            AFF aff; // A single character of affinity
                            for (int aIdx = 0; aIdx < affinity.Length; aIdx++) //: while ((aff = *(affinity++)) != 0)
                            {
                                aff = (AFF)affinity[aIdx];
                                in1 = mems[op.P1 + aIdx];
                                //: Debug.Assert( in1 <= mems[Mems.length]);
                                Debug.Assert(E.MemIsValid(in1));
                                E.ExpandBlob(in1);
                                ApplyAffinity(in1, aff, encoding);
                                //: in1++;
                            }
                            break;
                        }
                    case OP.MakeRecord:
                        {
                            // Opcode: MakeRecord P1 P2 P3 P4 *
                            //
                            // Convert P2 registers beginning with P1 into the [record format] use as a data record in a database table or as a key
                            // in an index.  The OP_Column opcode can decode the record later.
                            //
                            // P4 may be a string that is P2 characters long.  The nth character of the string indicates the column affinity that should be used for the nth
                            // field of the index key.
                            //
                            // The mapping from character to affinity is given by the SQLITE_AFF_ macros defined in sqliteInt.h.
                            //
                            // If P4 is NULL then all index fields have the affinity NONE.

                            // Assuming the record contains N fields, the record format looks like this:
                            //
                            // ------------------------------------------------------------------------
                            // | hdr-size | type 0 | type 1 | ... | type N-1 | data0 | ... | data N-1 | 
                            // ------------------------------------------------------------------------
                            //
                            // Data(0) is taken from register P1.  Data(1) comes from register P1+1 and so froth.
                            //
                            // Each type field is a varint representing the serial type of the corresponding data element (see sqlite3VdbeSerialType()). The
                            // hdr-size field is also a varint which is the offset from the beginning of the record to data0.
                            ulong dataLength = 0; // Number of bytes of data space
                            int hdrLength = 0; // Number of bytes of header space
                            int zeros = 0; // Number of zero bytes at the end of the record
                            int fields = op.P1; // Number of fields in the record
                            string affinity = (op.P4.Z ?? string.Empty); // The affinity string for the record
                            Debug.Assert(fields > 0 && op.P2 > 0 && op.P2 + fields <= Mems.length + 1);
                            //: Mem data0 = mems[fields]; // First field to be combined into the record
                            fields = op.P2;
                            //: Mem last =  data0[fields - 1]; // Last field of the record
                            int fileFormat = MinWriteFileFormat; // File format to use for encoding

                            // Identify the output register
                            Debug.Assert(op.P3 < op.P1 || op.P3 >= op.P1 + op.P2);
                            out_ = mems[op.P3];
                            MemAboutToChange(this, out_);

                            // Loop through the elements that will make up the record to figure out how much space is required for the new record.

                            Mem rec; // The new record
                            uint serialType; // Type field
                            for (int d0 = 0; d0 < fields; d0++)
                            {
                                rec = mems[op.P1 + d0];
                                Debug.Assert(E.MemIsValid(rec));
                                if (d0 < affinity.Length && affinity[d0] != '\0')
                                    ApplyAffinity(rec, (AFF)affinity[d0], encoding);
                                if ((rec.Flags & MEM.Zero) != 0 && rec.N > 0)
                                    MemExpandBlob(rec);
                                serialType = SerialType(rec, fileFormat);
                                int len = (int)SerialTypeLen(serialType); // Length of a field
                                dataLength += (ulong)len;
                                hdrLength += ConvertEx.GetVarintLength(serialType);
                                if ((rec.Flags & MEM.Zero) != 0)
                                    zeros += rec.u.Zeros; // Only pure zero-filled BLOBs can be input to this Opcode. We do not allow blobs with a prefix and a zero-filled tail.
                                else if (len != 0)
                                    zeros = 0;
                            }

                            // Add the initial header varint and total the size
                            int varintLength; // Number of bytes in a varint
                            hdrLength += varintLength = ConvertEx.GetVarintLength((ulong)hdrLength);
                            if (varintLength < ConvertEx.GetVarintLength((ulong)hdrLength))
                                hdrLength++;
                            long bytes = (long)((ulong)hdrLength + dataLength - (ulong)zeros); // Data space required for this record
                            if (bytes > ctx.Limits[(int)LIMIT.LENGTH])
                                goto too_big;

                            // Make sure the output register has a buffer large enough to store the new record. The output register (op->P3) is not allowed to
                            // be one of the input registers (because the following call to sqlite3VdbeMemGrow() could clobber the value before it is used).
                            //: if (MemGrow(out_, (int)bytes, 0) != 0)
                            //:     goto no_mem;
                            byte[] newRecord = C._alloc((int)bytes); //: out_.Z; // A buffer to hold the data for the new record

                            // Write the record
                            int i = ConvertEx.PutVarint32(newRecord, hdrLength); // Space used in zNewRecord[]
                            for (int d0 = 0; d0 < fields; d0++)
                            {
                                rec = mems[op.P1 + d0];
                                serialType = SerialType(rec, fileFormat);
                                i += ConvertEx.PutVarint32(newRecord, i, (int)serialType); // serial type
                            }
                            for (int d0 = 0; d0 < fields; d0++) // serial data
                            {
                                rec = mems[op.P1 + d0];
                                i += (int)SerialPut(newRecord, i, (int)bytes - i, rec, fileFormat);
                            }
                            Debug.Assert(i == bytes);

                            Debug.Assert(op.P3 > 0 && op.P3 <= Mems.length);
                            out_.Z_ = newRecord;
                            out_.Z = null;
                            out_.N = (int)bytes;
                            out_.Flags = MEM.Blob | MEM.Dyn;
                            out_.Del = null;
                            if (zeros != 0)
                            {
                                out_.u.Zeros = zeros;
                                out_.Flags |= MEM.Zero;
                            }
                            out_.Encode = TEXTENCODE.UTF8; // In case the blob is ever converted to text
                            REGISTER_TRACE(p, op.P3, out_);
                            UPDATE_MAX_BLOBSIZE(out_);
                            break;
                        }
#if !OMIT_BTREECOUNT
                    case OP.Count: // out2-prerelease
                        {
                            // Opcode: Count P1 P2 * * *
                            //
                            // Store the number of entries (an integer value) in the table or index opened by cursor P1 in register P2
                            long entrys = 0;
                            Btree.BtCursor crsr = p.apCsr[op.P1].pCursor;
                            if (crsr != null)
                                rc = Btree.Count(crsr, ref entrys);
                            else
                                entrys = 0;
                            out_.u.I = entrys;
                            break;
                        }
#endif
                    case OP.Savepoint:
                        {
                            // Opcode: Savepoint P1 * * P4 *
                            //
                            // Open, release or rollback the savepoint named by parameter P4, depending on the value of P1. To open a new savepoint, P1==0. To release (commit) an
                            // existing savepoint, P1==1, or to rollback an existing savepoint P1==2.
                            IPager.SAVEPOINT p1 = (IPager.SAVEPOINT)op.P1; // Value of P1 operand 
                            string name = op.P4.Z; // Name of savepoint

                            // Assert that the p1 parameter is valid. Also that if there is no open transaction, then there cannot be any savepoints.
                            Debug.Assert(ctx.Savepoints == null || ctx.AutoCommit == 0);
                            Debug.Assert(p1 == IPager.SAVEPOINT.BEGIN || p1 == IPager.SAVEPOINT.RELEASE || p1 == IPager.SAVEPOINT.ROLLBACK);
                            Debug.Assert(ctx.Savepoints != null || ctx.IsTransactionSavepoint == 0);
                            Debug.Assert(CheckSavepointCount(ctx) != 0);

                            if (p1 == IPager.SAVEPOINT.BEGIN)
                            {
                                if (ctx.WriteVdbeCnt > 0)
                                {
                                    // A new savepoint cannot be created if there are active write statements (i.e. open read/write incremental blob handles).
                                    C._setstring(ref ErrMsg, ctx, "cannot open savepoint - SQL statements in progress");
                                    rc = RC.BUSY;
                                }
                                else
                                {
                                    int nameLength = name.Length;

#if !OMIT_VIRTUALTABLE
                                    // This call is Ok even if this savepoint is actually a transaction savepoint (and therefore should not prompt xSavepoint()) callbacks.
                                    // If this is a transaction savepoint being opened, it is guaranteed that the ctx->aVTrans[] array is empty.
                                    Debug.Assert(ctx.AutoCommit == 0 || ctx.VTrans.length == 0);
                                    rc = VTable.Savepoint(ctx, IPager.SAVEPOINT.BEGIN, ctx.Statements + ctx.SavepointsLength);
                                    if (rc != RC.OK) goto abort_due_to_error;
#endif

                                    // Create a new savepoint structure.
                                    Savepoint newSavepoint = new Savepoint();
                                    if (newSavepoint != null)
                                    {
                                        newSavepoint.Name = name;

                                        // If there is no open transaction, then mark this as a special "transaction savepoint".
                                        if (ctx.AutoCommit != 0)
                                        {
                                            ctx.AutoCommit = 0;
                                            ctx.IsTransactionSavepoint = 1;
                                        }
                                        else
                                            ctx.SavepointsLength++;

                                        // Link the new savepoint into the database handle's list.
                                        newSavepoint.Next = ctx.Savepoints;
                                        ctx.Savepoints = newSavepoint;
                                        newSavepoint.DeferredCons = ctx.DeferredCons;
                                    }
                                }
                            }
                            else
                            {
                                // Find the named savepoint. If there is no such savepoint, then an an error is returned to the user.
                                int savepointId = 0;
                                Savepoint savepoint; for (savepoint = ctx.Savepoints; savepoint != null && !string.Equals(savepoint.Name, name, StringComparison.OrdinalIgnoreCase); savepoint = savepoint.Next)
                                    savepointId++;
                                if (savepoint == null)
                                {
                                    C._setstring(ref ErrMsg, ctx, "no such savepoint: %s", name);
                                    rc = RC.ERROR;
                                }
                                else if (ctx.WriteVdbeCnt > 0 || (p1 == IPager.SAVEPOINT.ROLLBACK && ctx.ActiveVdbeCnt > 1))
                                {
                                    // It is not possible to release (commit) a savepoint if there are active write statements.
                                    C._setstring(ref ErrMsg, ctx, "cannot %s savepoint - SQL statements in progress");
                                    rc = RC.BUSY;
                                }
                                else
                                {
                                    // Determine whether or not this is a transaction savepoint. If so, and this is a RELEASE command, then the current transaction is committed. 
                                    int isTransaction = (savepoint.Next == null && ctx.IsTransactionSavepoint != 0 ? 1 : 0);
                                    if (isTransaction != 0 && p1 == IPager.SAVEPOINT.RELEASE)
                                    {
                                        if ((rc = CheckFk(true)) != RC.OK)
                                            goto vdbe_return;
                                        ctx.AutoCommit = 1;
                                        if (Halt() == RC.BUSY)
                                        {
                                            PC = pc;
                                            ctx.AutoCommit = 0;
                                            RC_ = rc = RC.BUSY;
                                            goto vdbe_return;
                                        }
                                        ctx.IsTransactionSavepoint = 0;
                                        rc = RC_;
                                    }
                                    else
                                    {
                                        savepointId = ctx.SavepointsLength - savepointId - 1;
                                        int ii;
                                        if (p1 == IPager.SAVEPOINT.ROLLBACK)
                                            for (ii = 0; ii < ctx.DBs.length; ii++)
                                                ctx.DBs[ii].Bt.TripAllCursors(RC.ABORT);
                                        for (ii = 0; ii < ctx.DBs.length; ii++)
                                        {
                                            rc = ctx.DBs[ii].Bt.Savepoint(p1, savepointId);
                                            if (rc != RC.OK)
                                                goto abort_due_to_error;
                                        }
                                        if (p1 == IPager.SAVEPOINT.ROLLBACK && (ctx.Flags & Context.FLAG.InternChanges) != 0)
                                        {
                                            ExpirePreparedStatements(ctx);
                                            Parse.ResetAllSchemasOfConnection(ctx);
                                            ctx.Flags = (ctx.Flags | Context.FLAG.InternChanges);
                                        }
                                    }

                                    // Regardless of whether this is a RELEASE or ROLLBACK, destroy all savepoints nested inside of the savepoint being operated on.
                                    while (ctx.Savepoints != savepoint)
                                    {
                                        Savepoint tmp = ctx.Savepoints;
                                        ctx.Savepoints = tmp.Next;
                                        C._tagfree(ctx, ref tmp);
                                        ctx.SavepointsLength--;
                                    }

                                    // If it is a RELEASE, then destroy the savepoint being operated on too. If it is a ROLLBACK TO, then set the number of deferred 
                                    // constraint violations present in the database to the value stored when the savepoint was created.
                                    if (p1 == IPager.SAVEPOINT.RELEASE)
                                    {
                                        Debug.Assert(savepoint == ctx.Savepoints);
                                        ctx.Savepoints = savepoint.Next;
                                        C._tagfree(ctx, ref savepoint);
                                        if (isTransaction == 0)
                                            ctx.SavepointsLength--;
                                    }
                                    else
                                        ctx.DeferredCons = savepoint.DeferredCons;

                                    if (isTransaction == 0)
                                    {
                                        rc = VTable.Savepoint(ctx, p1, savepointId);
                                        if (rc != RC.OK) goto abort_due_to_error;
                                    }
                                }
                            }
                            break;
                        }
                    case OP.AutoCommit:
                        {
                            int desiredAutoCommit = (byte)op.P1;
                            int rollbackId = op.P2;
                            bool turnOnAC = (desiredAutoCommit != 0 && ctx.AutoCommit == 0);
                            Debug.Assert(desiredAutoCommit != 0 || desiredAutoCommit == 0);
                            Debug.Assert(desiredAutoCommit != 0 || rollbackId == 0);
                            Debug.Assert(ctx.ActiveVdbeCnt > 0); // At least this one VM is active
#if false
                            if (turnOnAC && rollbackId != 0 && ctx.ActiveVdbeCnt > 1)
                            {
                                // If this instruction implements a ROLLBACK and other VMs are still running, and a transaction is active, return an error indicating
                                // that the other VMs must complete first. 
                                C._setstring(ref ErrMsg, ctx, "cannot rollback transaction - SQL statements in progress");
                                rc = RC.BUSY;
                            }
                            else
#endif
                            if (turnOnAC && 0 == rollbackId && ctx.WriteVdbeCnt > 0)
                            {
                                // If this instruction implements a COMMIT and other VMs are writing return an error indicating that the other VMs must complete first. 
                                C._setstring(ref ErrMsg, ctx, "cannot commit transaction - SQL statements in progress");
                                rc = RC.BUSY;
                            }
                            else if (desiredAutoCommit != ctx.AutoCommit)
                            {
                                if (rollbackId != 0)
                                {
                                    Debug.Assert(desiredAutoCommit != 0);
                                    Main.RollbackAll(ctx, RC.ABORT_ROLLBACK);
                                    ctx.AutoCommit = 1;
                                }
                                else if ((rc = CheckFk(true)) != RC.OK)
                                    goto vdbe_return;
                                else
                                {
                                    ctx.AutoCommit = (byte)desiredAutoCommit;
                                    if (Halt() == RC.BUSY)
                                    {
                                        PC = pc;
                                        ctx.AutoCommit = (byte)(desiredAutoCommit == 0 ? 1 : 0);
                                        RC_ = rc = RC.BUSY;
                                        goto vdbe_return;
                                    }
                                }
                                Debug.Assert(ctx.Statements == 0);
                                Main.CloseSavepoints(ctx);
                                rc = (RC_ == RC.OK ? RC.DONE : RC.ERROR);
                                goto vdbe_return;
                            }
                            else
                            {
                                C._setstring(ref ErrMsg, ctx, (desiredAutoCommit == 0 ? "cannot start a transaction within a transaction" : (rollbackId != 0 ? "cannot rollback - no transaction is active" : "cannot commit - no transaction is active")));
                                rc = RC.ERROR;
                            }
                            break;
                        }
                    case OP.Transaction:
                        {
                            // Opcode: Transaction P1 P2 * * *
                            //
                            // Begin a transaction.  The transaction ends when a Commit or Rollback opcode is encountered.  Depending on the ON CONFLICT setting, the
                            // transaction might also be rolled back if an error is encountered.
                            //
                            // P1 is the index of the database file on which the transaction is started.  Index 0 is the main database file and index 1 is the
                            // file used for temporary tables.  Indices of 2 or more are used for attached databases.
                            //
                            // If P2 is non-zero, then a write-transaction is started.  A RESERVED lock is obtained on the database file when a write-transaction is started.  No
                            // other process can start another write transaction while this transaction is underway.  Starting a write transaction also creates a rollback journal. A
                            // write transaction must be started before any changes can be made to the database.  If P2 is 2 or greater then an EXCLUSIVE lock is also obtained
                            // on the file.
                            //
                            // If a write-transaction is started and the Vdbe.usesStmtJournal flag is true (this flag is set if the Vdbe may modify more than one row and may
                            // throw an ABORT exception), a statement transaction may also be opened. More specifically, a statement transaction is opened iff the database
                            // connection is currently not in autocommit mode, or if there are other active statements. A statement transaction allows the changes made by this
                            // VDBE to be rolled back after an error without having to roll back the entire transaction. If no error is encountered, the statement transaction
                            // will automatically commit when the VDBE halts.
                            //
                            // If P2 is zero, then a read-lock is obtained on the database file.
                            Debug.Assert(op.P1 >= 0 && op.P1 < ctx.DBs.length);
                            Debug.Assert((BtreeMask & (((yDbMask)1) << op.P1)) != 0);
                            Btree bt = ctx.DBs[op.P1].Bt;
                            if (bt != null)
                            {
                                rc = bt.BeginTrans(op.P2);
                                if (rc == RC.BUSY)
                                {
                                    PC = pc;
                                    RC_ = rc = RC.BUSY;
                                    goto vdbe_return;
                                }
                                if (rc != RC.OK)
                                    goto abort_due_to_error;
                                if (op.P2 != 0 && UsesStmtJournal && (ctx.AutoCommit == 0 || ctx.ActiveVdbeCnt > 1))
                                {
                                    Debug.Assert(bt.IsInTrans());
                                    if (StatementID == 0)
                                    {
                                        Debug.Assert(ctx.Statements >= 0 && ctx.SavepointsLength >= 0);
                                        ctx.Statements++;
                                        StatementID = ctx.SavepointsLength + ctx.Statements;
                                    }
                                    rc = VTable.Savepoint(ctx, IPager.SAVEPOINT.BEGIN, StatementID - 1);
                                    if (rc == RC.OK)
                                        rc = bt.BeginStmt(StatementID);
                                    // Store the current value of the database handles deferred constraint counter. If the statement transaction needs to be rolled back,
                                    // the value of this counter needs to be restored too.
                                    StmtDefCons = ctx.DeferredCons;
                                }
                            }
                            break;
                        }
                    case OP.ReadCookie: // out2-prerelease
                        {
                            // Opcode: ReadCookie P1 P2 P3 * *
                            //
                            // Read cookie number P3 from database P1 and write it into register P2. P3==1 is the schema version.  P3==2 is the database format.
                            // P3==3 is the recommended pager cache size, and so forth.  P1==0 is the main database file and P1==1 is the database file used to store
                            // temporary tables.
                            //
                            // There must be a read-lock on the database (either a transaction must be started or there must be an open cursor) before
                            // executing this instruction.
                            int db = op.P1;
                            Btree.META cookie = (Btree.META)op.P3;
                            Debug.Assert(op.P3 < Btree.N_BTREE_META);
                            Debug.Assert(db >= 0 && db < ctx.DBs.length);
                            Debug.Assert(ctx.DBs[db].Bt != null);
                            Debug.Assert((BtreeMask & (((yDbMask)1) << db)) != 0);
                            uint meta = 0;
                            ctx.DBs[db].Bt.GetMeta(cookie, ref meta);
                            out_.u.I = (int)meta;
                            break;
                        }
                    case OP.SetCookie: // in3
                        {
                            Debug.Assert(op.P2 < Btree.N_BTREE_META);
                            Debug.Assert(op.P1 >= 0 && op.P1 < ctx.DBs.length);
                            Debug.Assert((BtreeMask & (((yDbMask)1) << op.P1)) != 0);
                            Context.DB db = ctx.DBs[op.P1];
                            Debug.Assert(db.Bt != null);
                            Debug.Assert(Btree.SchemaMutexHeld(ctx, op.P1, null));
                            in3 = mems[op.P3];
                            MemIntegerify(in3);
                            // See note about index shifting on OP_ReadCookie
                            rc = db.Bt.UpdateMeta((Btree.META)op.P2, (uint)in3.u.I);
                            if ((Btree.META)op.P2 == Btree.META.SCHEMA_VERSION)
                            {
                                // When the schema cookie changes, record the new cookie internally
                                db.Schema.SchemaCookie = (int)in3.u.I;
                                ctx.Flags |= Context.FLAG.InternChanges;
                            }
                            else if ((Btree.META)op.P2 == Btree.META.FILE_FORMAT)
                                // Record changes in the file format
                                db.Schema.FileFormat = (byte)in3.u.I;
                            if (op.P1 == 1)
                            {
                                // Invalidate all prepared statements whenever the TEMP database schema is changed.  Ticket #1644
                                ExpirePreparedStatements(ctx);
                                Expired = false;
                            }
                            break;
                        }
                    case OP.VerifyCookie:
                        {
                            // Opcode: VerifyCookie P1 P2 P3 * *
                            //
                            // Check the value of global database parameter number 0 (the schema version) and make sure it is equal to P2 and that the
                            // generation counter on the local schema parse equals P3.
                            //
                            // P1 is the database number which is 0 for the main database file and 1 for the file holding temporary tables and some higher number
                            // for auxiliary databases.
                            //
                            // The cookie changes its value whenever the database schema changes. This operation is used to detect when that the cookie has changed
                            // and that the current process needs to reread the schema.
                            //
                            // Either a transaction needs to have been started or an OP_Open needs to be executed (to establish a read lock) before this opcode is
                            // invoked.
                            Debug.Assert(op.P1 >= 0 && op.P1 < ctx.DBs.length);
                            Debug.Assert((BtreeMask & ((yDbMask)1 << op.P1)) != 0);
                            Debug.Assert(Btree.SchemaMutexHeld(ctx, op.P1, null));
                            Btree bt = ctx.DBs[op.P1].Bt;
                            uint meta = 0;
                            uint gen;
                            if (bt != null)
                            {
                                bt.GetMeta(Btree.META.SCHEMA_VERSION, ref meta);
                                gen = (uint)ctx.DBs[op.P1].Schema.Generation;
                            }
                            else
                                gen = meta = 0;
                            if (meta != op.P2 || gen != op.P3)
                            {
                                C._tagfree(ctx, ref ErrMsg);
                                ErrMsg = "database schema has changed";
                                // If the schema-cookie from the database file matches the cookie stored with the in-memory representation of the schema, do
                                // not reload the schema from the database file.
                                //
                                // If virtual-tables are in use, this is not just an optimization. Often, v-tables store their data in other SQLite tables, which
                                // are queried from within xNext() and other v-table methods using prepared queries. If such a query is out-of-date, we do not want to
                                // discard the database schema, as the user code implementing the v-table would have to be ready for the sqlite3_vtab structure itself
                                // to be invalidated whenever sqlite3_step() is called from within a v-table method.
                                if (ctx.DBs[op.P1].Schema.SchemaCookie != meta)
                                    Parse.ResetOneSchema(ctx, op.P1);

                                Expired = true;
                                rc = RC.SCHEMA;
                            }
                            break;
                        }
                    case OP.OpenRead:
                    case OP.OpenWrite:
                        {
                            // Opcode: OpenRead P1 P2 P3 P4 P5
                            //
                            // Open a read-only cursor for the database table whose root page is P2 in a database file.  The database file is determined by P3. 
                            // P3==0 means the main database, P3==1 means the database used for temporary tables, and P3>1 means used the corresponding attached
                            // database.  Give the new cursor an identifier of P1.  The P1 values need not be contiguous but all P1 values should be small integers.
                            // It is an error for P1 to be negative.
                            //
                            // If P5!=0 then use the content of register P2 as the root page, not the value of P2 itself.
                            //
                            // There will be a read lock on the database whenever there is an open cursor.  If the database was unlocked prior to this instruction
                            // then a read lock is acquired as part of this instruction.  A read lock allows other processes to read the database but prohibits
                            // any other process from modifying the database.  The read lock is released when all cursors are closed.  If this instruction attempts
                            // to get a read lock but fails, the script terminates with an SQLITE_BUSY error code.
                            //
                            // The P4 value may be either an integer (P4_INT32) or a pointer to a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
                            // structure, then said structure defines the content and collating sequence of the index being opened. Otherwise, if P4 is an integer 
                            // value, it is set to the number of columns in the table.
                            //
                            // See also OpenWrite.
                            //
                            // Opcode: OpenWrite P1 P2 P3 P4 P5
                            //
                            // Open a read/write cursor named P1 on the table or index whose root page is P2.  Or if P5!=0 use the content of register P2 to find the
                            // root page.
                            //
                            // The P4 value may be either an integer (P4_INT32) or a pointer to a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
                            // structure, then said structure defines the content and collating sequence of the index being opened. Otherwise, if P4 is an integer 
                            // value, it is set to the number of columns in the table, or to the largest index of any column of the table that is actually used.
                            //
                            // This instruction works just like OpenRead except that it opens the cursor in read/write mode.  For a given table, there can be one or more read-only
                            // cursors or a single read/write cursor but not both.
                            //
                            // See also OpenRead.
                            Debug.Assert(((OPFLAG)op.P5 & (OPFLAG.P2ISREG | OPFLAG.BULKCSR)) == (OPFLAG)op.P5);
                            Debug.Assert(op.Opcode == OP.OpenWrite || op.P5 == 0);
                            if (Expired)
                            {
                                rc = RC.ABORT;
                                break;
                            }

                            int fields = 0;
                            KeyInfo keyInfo = null;
                            int p2 = op.P2;
                            int db = op.P3;
                            Debug.Assert(db >= 0 && db < ctx.DBs.length);
                            Debug.Assert((BtreeMask & (((yDbMask)1) << db)) != 0);
                            Context.DB dbAsObj = ctx.DBs[db];
                            Btree x = dbAsObj.Bt;
                            Debug.Assert(x != null);
                            int wrFlag;
                            if (op.Opcode == OP.OpenWrite)
                            {
                                wrFlag = 1;
                                Debug.Assert(Btree.SchemaMutexHeld(ctx, db, null));
                                if (dbAsObj.Schema.FileFormat < MinWriteFileFormat)
                                    MinWriteFileFormat = dbAsObj.Schema.FileFormat;
                            }
                            else
                                wrFlag = 0;
                            if (((OPFLAG)op.P5 & OPFLAG.P2ISREG) != 0)
                            {
                                Debug.Assert(p2 > 0);
                                Debug.Assert(p2 <= Mems.length);
                                in2 = mems[p2];
                                Debug.Assert(E.MemIsValid(in2));
                                Debug.Assert((in2.Flags & MEM.Int) != 0);
                                MemIntegerify(in2);
                                p2 = (int)in2.u.I;
                                // The p2 value always comes from a prior OP_CreateTable opcode and that opcode will always set the p2 value to 2 or more or else fail.
                                // If there were a failure, the prepared statement would have halted before reaching this instruction.
                                if (C._NEVER(p2 < 2))
                                {
                                    rc = SysEx.CORRUPT_BKPT();
                                    goto abort_due_to_error;
                                }
                            }
                            if (op.P4Type == P4T.KEYINFO)
                            {
                                keyInfo = op.P4.KeyInfo;
                                keyInfo.Encode = E.CTXENCODE(ctx);
                                fields = keyInfo.Fields + 1;
                            }
                            else if (op.P4Type == P4T.INT32)
                                fields = op.P4.I;
                            Debug.Assert(op.P1 >= 0);
                            VdbeCursor cur = AllocateCursor(this, op.P1, fields, db, true);
                            if (cur == null) goto no_mem;
                            cur.NullRow = true;
                            cur.IsOrdered = true;
                            rc = x.Cursor(p2, wrFlag, keyInfo, cur.Cursor);
                            cur.KeyInfo = keyInfo;
                            Debug.Assert(OPFLAG.BULKCSR == BTREE_BULKLOAD);

                            // Since it performs no memory allocation or IO, the only value that sqlite3BtreeCursor() may return is SQLITE_OK.
                            Debug.Assert(rc == RC.OK);

                            // Set the VdbeCursor.isTable and isIndex variables. Previous versions of SQLite used to check if the root-page flags were sane at this point
                            // and report database corruption if they were not, but this check has since moved into the btree layer.
                            cur.IsTable = (op.P4Type != P4T.KEYINFO);
                            cur.IsIndex = !cur.IsTable;
                            break;
                        }
                    case OP.OpenAutoindex:
                    case OP.OpenEphemeral:
                        {
                            // Opcode: OpenEphemeral P1 P2 * P4 P5
                            //
                            // Open a new cursor P1 to a transient table. The cursor is always opened read/write even if 
                            // the main database is read-only.  The ephemeral table is deleted automatically when the cursor is closed.
                            //
                            // P2 is the number of columns in the ephemeral table. The cursor points to a BTree table if P4==0 and to a BTree index
                            // if P4 is not 0.  If P4 is not NULL, it points to a KeyInfo structure that defines the format of keys in the index.
                            //
                            // This opcode was once called OpenTemp.  But that created confusion because the term "temp table", might refer either
                            // to a TEMP table at the SQL level, or to a table opened by this opcode.  Then this opcode was call OpenVirtual.  But
                            // that created confusion with the whole virtual-table idea.
                            //
                            // The P5 parameter can be a mask of the BTREE_* flags defined in btree.h.  These flags control aspects of the operation of
                            // the btree.  The BTREE_OMIT_JOURNAL and BTREE_SINGLE flags are added automatically.
                            //
                            // Opcode: OpenAutoindex P1 P2 * P4 *
                            //
                            // This opcode works the same as OP_OpenEphemeral.  It has a different name to distinguish its use.  Tables created using
                            // by this opcode will be used for automatically created transient indices in joins.
                            const VSystem.OPEN vfsFlags = VSystem.OPEN.READWRITE | VSystem.OPEN.CREATE | VSystem.OPEN.EXCLUSIVE | VSystem.OPEN.DELETEONCLOSE | VSystem.OPEN.TRANSIENT_DB;
                            Debug.Assert(op.P1 >= 0);
                            VdbeCursor cx = AllocateCursor(this, op.P1, op.P2, -1, true);
                            if (cx == null)
                                goto no_mem;
                            cx.NullRow = true;
                            rc = Btree.Open(ctx.Vfs, null, ctx, ref cx.Bt, Btree.OPEN.OMIT_JOURNAL | Btree.OPEN.SINGLE | (Btree.OPEN)op.P5, vfsFlags);
                            if (rc == RC.OK)
                                rc = cx.Bt.BeginTrans(1);
                            if (rc == RC.OK)
                            {
                                // If a transient index is required, create it by calling sqlite3BtreeCreateTable() with the BTREE_BLOBKEY flag before
                                // opening it. If a transient table is required, just use the automatically created table with root-page 1 (an BLOB_INTKEY table).
                                if (op.P4.KeyInfo != null)
                                {
                                    Debug.Assert(op.P4Type == P4T.KEYINFO);
                                    int pgno = 0;
                                    rc = Btree.CreateTable(cx.Bt, ref pgno, BTREE_BLOBKEY);
                                    if (rc == RC.OK)
                                    {
                                        Debug.Assert(pgno == MASTER_ROOT + 1);
                                        rc = cx.Bt.Cursor(pgno, 1, op.P4.KeyInfo, cx.Cursor);
                                        cx.KeyInfo = op.P4.KeyInfo;
                                        cx.KeyInfo.Encode = E.CTXENCODE(ctx);
                                    }
                                    cx.IsTable = false;
                                }
                                else
                                {
                                    rc = cx.Bt.Cursor(MASTER_ROOT, 1, null, cx.Cursor);
                                    cx.IsTable = true;
                                }
                            }
                            cx.IsOrdered = (op.P5 != BTREE_UNORDERED);
                            cx.IsIndex = !cx.IsTable;
                            break;
                        }
                    case OP.SorterOpen:
                        {
                            // Opcode: SorterOpen P1 P2 * P4 *
                            //
                            // This opcode works like OP_OpenEphemeral except that it opens a transient index that is specifically designed to sort large
                            // tables using an external merge-sort algorithm.
                            VdbeCursor cur = AllocateCursor(this, op.P1, op.P2, -1, true);
                            if (cur == null) goto no_mem;
                            cur.KeyInfo = op.P4.KeyInfo;
                            cur.KeyInfo.Encode = E.CTXENCODE(ctx);
                            cur.IsSorter = true;
                            rc = SorterInit(ctx, cur);
                            break;
                        }
                    case OP.OpenPseudo:
                        {
                            // Opcode: OpenPseudo P1 P2 P3 * P5
                            //
                            // Open a new cursor that points to a fake table that contains a single row of data.  The content of that one row in the content of memory
                            // register P2 when P5==0.  In other words, cursor P1 becomes an alias for the MEM_Blob content contained in register P2.  When P5==1, then the
                            // row is represented by P3 consecutive registers beginning with P2.
                            //
                            // A pseudo-table created by this opcode is used to hold a single row output from the sorter so that the row can be decomposed into
                            // individual columns using the OP_Column opcode.  The OP_Column opcode is the only cursor opcode that works with a pseudo-table.
                            //
                            // P3 is the number of fields in the records that will be stored by the pseudo-table.
                            Debug.Assert(op.P1 >= 0);
                            VdbeCursor cur = AllocateCursor(this, op.P1, op.P3, -1, false);
                            if (cur == null) goto no_mem;
                            cur.NullRow = true;
                            cur.PseudoTableReg = op.P2;
                            cur.IsTable = true;
                            cur.IsIndex = false;
                            cur.MultiPseudo = op.P5;
                            break;
                        }
                    case OP.Close:
                        {
                            // Opcode: Close P1 * * * *
                            //
                            // Close a cursor previously opened as P1.  If P1 is not currently open, this instruction is a no-op.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            FreeCursor(Cursors[op.P1]);
                            Cursors[op.P1] = null;
                            break;
                        }
                    case OP.SeekLt: // jump, in3
                    case OP.SeekLe: // jump, in3
                    case OP.SeekGe: // jump, in3
                    case OP.SeekGt: // jump, in3
                        {
                            // Opcode: SeekGe P1 P2 P3 P4 *
                            //
                            // If cursor P1 refers to an SQL table (B-Tree that uses integer keys), use the value in register P3 as the key.  If cursor P1 refers 
                            // to an SQL index, then P3 is the first in an array of P4 registers that are used as an unpacked index key. 
                            //
                            // Reposition cursor P1 so that  it points to the smallest entry that is greater than or equal to the key value. If there are no records 
                            // greater than or equal to the key and P2 is not zero, then jump to P2.
                            //
                            // See also: Found, NotFound, Distinct, SeekLt, SeekGt, SeekLe
                            //
                            // Opcode: SeekGt P1 P2 P3 P4 *
                            //
                            // If cursor P1 refers to an SQL table (B-Tree that uses integer keys), use the value in register P3 as a key. If cursor P1 refers 
                            // to an SQL index, then P3 is the first in an array of P4 registers that are used as an unpacked index key. 
                            //
                            // Reposition cursor P1 so that  it points to the smallest entry that is greater than the key value. If there are no records greater than 
                            // the key and P2 is not zero, then jump to P2.
                            //
                            // See also: Found, NotFound, Distinct, SeekLt, SeekGe, SeekLe
                            //
                            // Opcode: SeekLt P1 P2 P3 P4 * 
                            //
                            // If cursor P1 refers to an SQL table (B-Tree that uses integer keys), use the value in register P3 as a key. If cursor P1 refers 
                            // to an SQL index, then P3 is the first in an array of P4 registers that are used as an unpacked index key. 
                            //
                            // Reposition cursor P1 so that  it points to the largest entry that is less than the key value. If there are no records less than 
                            // the key and P2 is not zero, then jump to P2.
                            //
                            // See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLe
                            //
                            // Opcode: SeekLe P1 P2 P3 P4 *
                            //
                            // If cursor P1 refers to an SQL table (B-Tree that uses integer keys), use the value in register P3 as a key. If cursor P1 refers 
                            // to an SQL index, then P3 is the first in an array of P4 registers that are used as an unpacked index key. 
                            //
                            // Reposition cursor P1 so that it points to the largest entry that is less than or equal to the key value. If there are no records 
                            // less than or equal to the key and P2 is not zero, then jump to P2.
                            //
                            // See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLt
                            int res = 0;
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            Debug.Assert(op.P2 != 0);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.PseudoTableReg == 0);
                            Debug.Assert(OP.SeekLe == OP.SeekLt + 1);
                            Debug.Assert(OP.SeekGe == OP.SeekLt + 2);
                            Debug.Assert(OP.SeekGt == OP.SeekLt + 3);
                            Debug.Assert(cur.IsOrdered);
                            UnpackedRecord r = new UnpackedRecord();
                            if (cur.Cursor != null)
                            {
                                OP oc = op.Opcode;
                                cur.NullRow = false;
                                if (cur.IsTable)
                                {
                                    // The input value in P3 might be of any type: integer, real, string, blob, or NULL.  But it needs to be an integer before we can do the seek, so covert it.
                                    in3 = mems[op.P3];
                                    ApplyNumericAffinity(in3);
                                    long keyId = IntValue(in3); // The rowid we are to seek to
                                    cur.RowidIsValid = false;

                                    // If the P3 value could not be converted into an integer without loss of information, then special processing is required...
                                    if ((in3.Flags & MEM.Int) == 0)
                                    {
                                        if ((in3.Flags & MEM.Real) == 0)
                                        {
                                            // If the P3 value cannot be converted into any kind of a number, then the seek is not possible, so jump to P2
                                            pc = op.P2 - 1;
                                            break;
                                        }
                                        // If we reach this point, then the P3 value must be a floating point number.
                                        Debug.Assert((in3.Flags & MEM.Real) != 0);

                                        if (keyId == long.MinValue && (in3.R < (double)keyId || in3.R > 0))
                                        {
                                            // The P3 value is too large in magnitude to be expressed as an integer.
                                            res = 1;
                                            if (in3.R < 0)
                                            {
                                                if (oc >= OP.SeekGe)
                                                {
                                                    Debug.Assert(oc == OP.SeekGe || oc == OP.SeekGt);
                                                    rc = Btree.First(cur.Cursor, ref res);
                                                    if (rc != RC.OK)
                                                        goto abort_due_to_error;
                                                }
                                            }
                                            else
                                            {
                                                if (oc <= OP.SeekLe)
                                                {
                                                    Debug.Assert(oc == OP.SeekLt || oc == OP.SeekLe);
                                                    rc = Btree.Last(cur.Cursor, ref res);
                                                    if (rc != RC.OK)
                                                        goto abort_due_to_error;
                                                }
                                            }
                                            if (res != 0)
                                                pc = op.P2 - 1;
                                            break;
                                        }
                                        else if (oc == OP.SeekLt || oc == OP.SeekGe)
                                        {
                                            // Use the ceiling() function to convert real.int
                                            if (in3.R > (double)keyId) keyId++;
                                        }
                                        else
                                        {
                                            // Use the floor() function to convert real.int
                                            Debug.Assert(oc == OP.SeekLe || oc == OP.SeekGt);
                                            if (in3.R < (double)keyId) keyId--;
                                        }
                                    }
                                    rc = Btree.MovetoUnpacked(cur.Cursor, null, keyId, 0, ref res);
                                    if (rc != RC.OK)
                                        goto abort_due_to_error;
                                    if (res == 0)
                                    {
                                        cur.RowidIsValid = true;
                                        cur.LastRowid = keyId;
                                    }
                                }
                                else
                                {
                                    int fields = op.P4.I;
                                    Debug.Assert(op.P4Type == P4T.INT32);
                                    Debug.Assert(fields > 0);
                                    r.KeyInfo = cur.KeyInfo;
                                    r.Fields = (ushort)fields;

                                    // The next line of code computes as follows, only faster:
                                    //   r.Flags = (oc == OP_SeekGt || oc == OP_SeekLe ? UNPACKED_INCRKEY : 0);
                                    r.Flags = (UNPACKED)((int)UNPACKED.INCRKEY * (1 & ((int)oc - (int)OP.SeekLt)));
                                    Debug.Assert(oc != OP.SeekGt || r.Flags == UNPACKED.INCRKEY);
                                    Debug.Assert(oc != OP.SeekLe || r.Flags == UNPACKED.INCRKEY);
                                    Debug.Assert(oc != OP.SeekGe || r.Flags == 0);
                                    Debug.Assert(oc != OP.SeekLt || r.Flags == 0);

                                    r.Mems = new Mem[r.Fields]; for (int i = 0; i < r.Fields; i++)
                                    {
                                        r.Mems[i] = mems[op.P3 + i]; //: r.mems = mems[op.P3];
#if DEBUG
                                        Debug.Assert(E.MemIsValid(r.Mems[i]));
#endif
                                    }
                                    E.ExpandBlob(r.Mems[0]);
                                    rc = Btree.MovetoUnpacked(cur.Cursor, r, 0, 0, ref res);
                                    if (rc != RC.OK)
                                        goto abort_due_to_error;
                                    cur.RowidIsValid = false;
                                }
                                cur.DeferredMoveto = false;
                                cur.CacheStatus = CACHE_STALE;
#if TEST
                                f_search_count++;
#endif
                                if (oc >= OP.SeekGe)
                                {
                                    Debug.Assert(oc == OP.SeekGe || oc == OP.SeekGt);
                                    if (res < 0 || (res == 0 && oc == OP.SeekGt))
                                    {
                                        rc = Btree.Next(cur.Cursor, ref res);
                                        if (rc != Rc.OK) goto abort_due_to_error;
                                        cur.RowidIsValid = false;
                                    }
                                    else
                                        res = 0;
                                }
                                else
                                {
                                    Debug.Assert(oc == OP.SeekLt || oc == OP.SeekLe);
                                    if (res > 0 || (res == 0 && oc == OP.SeekLt))
                                    {
                                        rc = Btree.Previous(cur.Cursor, ref res);
                                        if (rc != RC.OK) goto abort_due_to_error;
                                        cur.RowidIsValid = false;
                                    }
                                    else
                                        res = (Btree.Eof(cur.Cursor) ? 1 : 0); // res might be negative because the table is empty.  Check to see if this is the case.
                                }
                                Debug.Assert(op.P2 > 0);
                                if (res != 0)
                                    pc = op.P2 - 1;
                            }
                            else
                                // This happens when attempting to open the sqlite3_master table for read access returns SQLITE_EMPTY. In this case always
                                // take the jump (since there are no records in the table).
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.Seek: // in2
                        {
                            // Opcode: Seek P1 P2 * * *
                            //
                            // P1 is an open table cursor and P2 is a rowid integer.  Arrange for P1 to move so that it points to the rowid given by P2.
                            //
                            // This is actually a deferred seek.  Nothing actually happens until the cursor is used to read a record.  That way, if no reads
                            // occur, no unnecessary I/O happens.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(C._ALWAYS(cur != null));
                            if (cur.Cursor != null)
                            {
                                Debug.Assert(cur.IsTable);
                                cur.NullRow = false;
                                in2 = mems[op.P2];
                                cur.MovetoTarget = IntValue(in2);
                                cur.RowidIsValid = false;
                                cur.DeferredMoveto = true;
                            }
                            break;
                        }
                    case OP.NotFound: // jump, in3
                    case OP.Found: // jump, in3
                        {
                            // Opcode: Found P1 P2 P3 P4 *
                            //
                            // If P4==0 then register P3 holds a blob constructed by MakeRecord.  If P4>0 then register P3 is the first of P4 registers that form an unpacked record.
                            //
                            // Cursor P1 is on an index btree.  If the record identified by P3 and P4 is a prefix of any entry in P1 then a jump is made to P2 and
                            // P1 is left pointing at the matching entry.
                            //
                            // Opcode: NotFound P1 P2 P3 P4 *
                            //
                            // If P4==0 then register P3 holds a blob constructed by MakeRecord.  If P4>0 then register P3 is the first of P4 registers that form an unpacked record.
                            // 
                            // Cursor P1 is on an index btree.  If the record identified by P3 and P4 is not the prefix of any entry in P1 then a jump is made to P2.  If P1 
                            // does contain an entry whose prefix matches the P3/P4 record then control falls through to the next instruction and P1 is left pointing at the matching entry.
                            //
                            // See also: Found, NotExists, IsUnique
                            int res = 0;
#if TEST
                            g_found_count++;
#endif
                            bool alreadyExists = false;
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            Debug.Assert(op.P4Type == Vdbe.P4T.INT32);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            in3 = mems[op.P3];
                            if (C._ALWAYS(cur.Cursor != null))
                            {
                                Debug.Assert(!cur.IsTable);
                                UnpackedRecord idxKey;
                                UnpackedRecord r = new UnpackedRecord();
                                if (op.P4.I > 0)
                                {
                                    r.KeyInfo = cur.KeyInfo;
                                    r.Fields = (ushort)op.P4.I;
                                    r.Mems = new Mem[r.Fields]; for (int i = 0; i < r.Mems.Length; i++)
                                    {
                                        r.Mems[i] = mems[op.P3 + i]; //: r.mems = mems[op.P3];
#if DEBUG
                                        Debug.Assert(E.MemIsValid(r.Mems[i]));
#endif
                                    }
                                    r.Flags = UNPACKED.PREFIX_MATCH;
                                    idxKey = r;
                                }
                                else
                                {
                                    //UnpackedRecord tempRecs = new UnpackedRecord();
                                    idxKey = AllocUnpackedRecord(cur.KeyInfo);
                                    if (idxKey == null) goto no_mem;
                                    Debug.Assert((in3.Flags & MEM.Blob) != 0);
                                    Debug.Assert((in3.Flags & MEM.Zero) == 0); // zeroblobs already expanded
                                    idxKey = RecordUnpack(cur.KeyInfo, in3.N, in3.Z_, idxKey);
                                    idxKey.Flags |= UNPACKED.PREFIX_MATCH;
                                }
                                rc = Btree.MovetoUnpacked(cur.Cursor, idxKey, 0, 0, ref res);
                                //if (op.P4.I == 0)
                                //    DeleteUnpackedRecord(idxKey);
                                if (rc != RC.OK)
                                    break;
                                alreadyExists = (res == 0);
                                cur.DeferredMoveto = false;
                                cur.CacheStatus = CACHE_STALE;
                            }
                            if (op.Opcode == OP.Found)
                            {
                                if (alreadyExists) pc = op.P2 - 1;
                            }
                            else
                            {
                                if (!alreadyExists) pc = op.P2 - 1;
                            }
                            break;
                        }
                    case OP.IsUnique: // jump, in3
                        {
                            // Opcode: IsUnique P1 P2 P3 P4 *
                            //
                            // Cursor P1 is open on an index b-tree - that is to say, a btree which no data and where the key are records generated by OP_MakeRecord with
                            // the list field being the integer ROWID of the entry that the index entry refers to.
                            //
                            // The P3 register contains an integer record number. Call this record number R. Register P4 is the first in a set of N contiguous registers
                            // that make up an unpacked index key that can be used with cursor P1. The value of N can be inferred from the cursor. N includes the rowid
                            // value appended to the end of the index record. This rowid value may or may not be the same as R.
                            //
                            // If any of the N registers beginning with register P4 contains a NULL value, jump immediately to P2.
                            //
                            // Otherwise, this instruction checks if cursor P1 contains an entry where the first (N-1) fields match but the rowid value at the end
                            // of the index entry is not R. If there is no such entry, control jumps to instruction P2. Otherwise, the rowid of the conflicting index
                            // entry is copied to register P3 and control falls through to the next instruction.
                            //
                            // See also: NotFound, NotExists, Found
                            in3 = mems[op.P3];
                            // Assert that the values of parameters P1 and P4 are in range.
                            Debug.Assert(op.P4Type == P4T.INT32);
                            Debug.Assert(op.P4.I > 0 && op.P4.I <= Mems.length);
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);

                            // Find the index cursor.
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(!cur.DeferredMoveto);
                            cur.SeekResult = 0;
                            cur.CacheStatus = CACHE_STALE;
                            Btree.BtCursor crsr = cur.Cursor;

                            // If any of the values are NULL, take the jump.
                            ushort fields = cur.KeyInfo.Fields;
                            Mem[] maxs = new Mem[fields + 1];
                            for (ushort ii = 0; ii < fields; ii++)
                            {
                                maxs[ii] = mems[op.P4.I + ii];
                                if ((maxs[ii].Flags & MEM.Null) != 0)
                                {
                                    pc = op.P2 - 1;
                                    crsr = null;
                                    break;
                                }
                            }
                            maxs[fields] = new Mem();
                            Debug.Assert((maxs[fields].Flags & MEM.Null) == 0);

                            if (crsr != null)
                            {
                                // Populate the index search key.
                                UnpackedRecord r = new UnpackedRecord(); // B-Tree index search key
                                r.KeyInfo = cur.KeyInfo;
                                r.Fields = (ushort)(fields + 1);
                                r.Flags = UNPACKED.PREFIX_SEARCH;
                                r.Mems = maxs;
#if DEBUG
                                for (int i = 0; i < r.Fields; i++) Debug.Assert(E.MemIsValid(r.Mems[i]));
#endif
                                // Extract the value of R from register P3.
                                MemIntegerify(in3);
                                long R = in3.u.I; // Rowid stored in register P3

                                // Search the B-Tree index. If no conflicting record is found, jump to P2. Otherwise, copy the rowid of the conflicting record to
                                // register P3 and fall through to the next instruction.
                                rc = Btree.MovetoUnpacked(crsr, r, 0, 0, ref cur.SeekResult);
                                if ((r.Flags & UNPACKED.PREFIX_SEARCH) != 0 || r.Rowid == R)
                                    pc = op.P2 - 1;
                                else
                                    in3.u.I = r.Rowid;
                            }
                            break;
                        }
                    case OP.NotExists: // jump, in3
                        {
                            // Opcode: NotExists P1 P2 P3 * *
                            //
                            // Use the content of register P3 as an integer key.  If a record with that key does not exist in table of P1, then jump to P2. 
                            // If the record does exist, then fall through.  The cursor is left pointing to the record if it exists.
                            //
                            // The difference between this operation and NotFound is that this operation assumes the key is an integer and that P1 is a table whereas
                            // NotFound assumes key is a blob constructed from MakeRecord and P1 is an index.
                            //
                            // See also: Found, NotFound, IsUnique
                            int res;
                            in3 = mems[op.P3];
                            Debug.Assert((in3.Flags & MEM.Int) != 0);
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.IsTable);
                            Debug.Assert(cur.PseudoTableReg == 0);
                            Btree.BtCursor crsr = cur.Cursor;
                            if (crsr != null)
                            {
                                res = 0;
                                long keyId = in3.u.I;
                                rc = Btree.MovetoUnpacked(crsr, null, (long)keyId, 0, ref res);
                                cur.LastRowid = in3.u.I;
                                cur.RowidIsValid = (res == 0);
                                cur.NullRow = false;
                                cur.CacheStatus = CACHE_STALE;
                                cur.DeferredMoveto = false;
                                if (res != 0)
                                {
                                    pc = op.P2 - 1;
                                    Debug.Assert(!cur.RowidIsValid);
                                }
                                cur.SeekResult = res;
                            }
                            else
                            {
                                // This happens when an attempt to open a read cursor on the sqlite_master table returns SQLITE_EMPTY.
                                pc = op.P2 - 1;
                                Debug.Assert(!cur.RowidIsValid);
                                cur.SeekResult = 0;
                            }
                            break;
                        }
                    case OP.Sequence:// out2-prerelease
                        {
                            // Opcode: Sequence P1 P2 * * *
                            //
                            // Find the next available sequence number for cursor P1. Write the sequence number into register P2.
                            // The sequence number on the cursor is incremented after this instruction.  
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            Debug.Assert(Cursors[op.P1] != null);
                            out_.u.I = (long)Cursors[op.P1].SeqCount++;
                            break;
                        }
                    case OP.NewRowid: // out2-prerelease
                        {
                            // Opcode: NewRowid P1 P2 P3 * *
                            //
                            // Get a new integer record number (a.k.a "rowid") used as the key to a table. The record number is not previously used as a key in the database
                            // table that cursor P1 points to.  The new record number is written written to register P2.
                            //
                            // If P3>0 then P3 is a register in the root frame of this VDBE that holds the largest previously generated record number. No new record numbers are
                            // allowed to be less than this value. When this value reaches its maximum, an SQLITE_FULL error is generated. The P3 register is updated with the '
                            // generated record number. This P3 mechanism is used to help implement the AUTOINCREMENT feature.
                            long v = 0; // The new rowid
                            int res = 0; // Result of an sqlite3BtreeLast()
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1]; // Cursor of table to get the new rowid
                            Debug.Assert(cur != null);
                            if (C._NEVER(cur.Cursor == null))
                            { } // The zero initialization above is all that is needed
                            else
                            {
#if _32BIT_ROWID                                
                                const int MAX_ROWID = int.MaxValue;
#else
                                const long MAX_ROWID = long.MaxValue; // Some compilers complain about constants of the form 0x7fffffffffffffff. Others complain about 0x7ffffffffffffffffLL.  The following macro seems to provide the constant while making all compilers happy.
#endif
                                // The next rowid or record number (different terms for the same thing) is obtained in a two-step algorithm.
                                //
                                // First we attempt to find the largest existing rowid and add one to that.  But if the largest existing rowid is already the maximum
                                // positive integer, we have to fall through to the second probabilistic algorithm
                                //
                                // The second algorithm is to select a rowid at random and see if it already exists in the table.  If it does not exist, we have
                                // succeeded.  If the random rowid does exist, we select a new one and try again, up to 100 times.
                                Debug.Assert(cur.IsTable);
                                if (!cur.UseRandomRowid)
                                {
                                    v = Btree.GetCachedRowid(cur.Cursor);
                                    if (v == 0)
                                    {
                                        rc = Btree.Last(cur.Cursor, ref res);
                                        if (rc != RC.OK)
                                            goto abort_due_to_error;
                                        if (res != 0)
                                            v = 1; // IMP: R-61914-48074
                                        else
                                        {
                                            Debug.Assert(Btree.CursorIsValid(cur.Cursor));
                                            rc = Btree.KeySize(cur.Cursor, ref v);
                                            Debug.Assert(rc == RC.OK); // Cannot fail following BtreeLast()
                                            if (v == MAX_ROWID)
                                                cur.UseRandomRowid = true;
                                            else
                                                v++; // IMP: R-29538-34987
                                        }
                                    }
#if !OMIT_AUTOINCREMENT
                                    if (op.P3 != 0)
                                    {
                                        // Assert that P3 is a valid memory cell.
                                        Debug.Assert(op.P3 > 0);
                                        Mem mem; // Register holding largest rowid for AUTOINCREMENT
                                        VdbeFrame frame; // Root frame of VDBE
                                        if (Frames != null)
                                        {
                                            for (frame = Frames; frame.Parent != null; frame = frame.Parent) ;
                                            // Assert that P3 is a valid memory cell.
                                            Debug.Assert(op.P3 <= frame.Mems.length);
                                            mem = frame.Mems[op.P3];
                                        }
                                        else
                                        {
                                            // Assert that P3 is a valid memory cell.
                                            Debug.Assert(op.P3 <= Mems.length);
                                            mem = mems[op.P3];
                                            MemAboutToChange(this, mem);
                                        }
                                        Debug.Assert(E.MemIsValid(mem));

                                        REGISTER_TRACE(op.P3, mem);
                                        MemIntegerify(mem);
                                        Debug.Assert((mem.Flags & MEM.Int) != 0); // mem(P3) holds an integer
                                        if (mem.u.I == MAX_ROWID || cur.UseRandomRowid)
                                        {
                                            rc = RC.FULL; // IMP: R-12275-61338
                                            goto abort_due_to_error;
                                        }
                                        if (v < (mem.u.I + 1))
                                            v = (int)(mem.u.I + 1);
                                        mem.u.I = (long)v;
                                    }
#endif

                                    Btree.SetCachedRowid(cur.Cursor, (v < MAX_ROWID ? v + 1 : 0));
                                }
                                if (cur.UseRandomRowid)
                                {
                                    // IMPLEMENTATION-OF: R-07677-41881 If the largest ROWID is equal to the largest possible integer (9223372036854775807) then the database
                                    // engine starts picking positive candidate ROWIDs at random until it finds one that is not previously used. */
                                    Debug.Assert(op.P3 == 0); // We cannot be in random rowid mode if this is an AUTOINCREMENT table. on the first attempt, simply do one more than previous
                                    v = lastRowid;
                                    v &= (MAX_ROWID >> 1); // ensure doesn't go negative
                                    v++; // ensure non-zero
                                    int cnt = 0; // Counter to limit the number of searches
                                    while ((rc = Btree.MovetoUnpacked(cur.Cursor, null, v, 0, ref res)) == RC.OK && res == 0 && ++cnt < 100)
                                    {
                                        // collision - try another random rowid
                                        SysEx.PutRandom(sizeof(long), ref v);
                                        if (cnt < 5)
                                            v &= 0xffffff; // try "small" random rowids for the initial attempts
                                        else
                                            v &= (MAX_ROWID >> 1); // ensure doesn't go negative
                                        v++; // ensure non-zero
                                    }
                                    if (rc == RC.OK && res == 0)
                                    {
                                        rc = RC.FULL; // IMP: R-38219-53002
                                        goto abort_due_to_error;
                                    }
                                    Debug.Assert(v > 0); // EV: R-40812-03570
                                }
                                cur.RowidIsValid = false;
                                cur.DeferredMoveto = false;
                                cur.CacheStatus = CACHE_STALE;
                            }
                            out_.u.I = (long)v;
                            break;
                        }
                    case OP.Insert:
                    case OP.InsertInt:
                        {
                            // Opcode: Insert P1 P2 P3 P4 P5
                            //
                            // Write an entry into the table of cursor P1.  A new entry is created if it doesn't already exist or the data for an existing
                            // entry is overwritten.  The data is the value MEM_Blob stored in register number P2. The key is stored in register P3. The key must
                            // be a MEM_Int.
                            //
                            // If the OPFLAG_NCHANGE flag of P5 is set, then the row change count is incremented (otherwise not).  If the OPFLAG_LASTROWID flag of P5 is set,
                            // then rowid is stored for subsequent return by the sqlite3_last_insert_rowid() function (otherwise it is unmodified).
                            //
                            // If the OPFLAG_USESEEKRESULT flag of P5 is set and if the result of the last seek operation (OP_NotExists) was a success, then this
                            // operation will not attempt to find the appropriate row before doing the insert but will instead overwrite the row that the cursor is
                            // currently pointing to.  Presumably, the prior OP_NotExists opcode has already positioned the cursor correctly.  This is an optimization
                            // that boosts performance by avoiding redundant seeks.
                            //
                            // If the OPFLAG_ISUPDATE flag is set, then this opcode is part of an UPDATE operation.  Otherwise (if the flag is clear) then this opcode
                            // is part of an INSERT operation.  The difference is only important to the update hook.
                            //
                            // Parameter P4 may point to a string containing the table-name, or may be NULL. If it is not NULL, then the update-hook 
                            // (sqlite3.xUpdateCallback) is invoked following a successful insert.
                            //
                            // (WARNING/TODO: If P1 is a pseudo-cursor and P2 is dynamically allocated, then ownership of P2 is transferred to the pseudo-cursor
                            // and register P2 becomes ephemeral.  If the cursor is changed, the value of register P2 will then change.  Make sure this does not
                            // cause any problems.)
                            //
                            // This instruction only works on tables.  The equivalent instruction for indices is OP_IdxInsert.
                            //
                            // Opcode: InsertInt P1 P2 P3 P4 P5
                            //
                            // This works exactly like OP_Insert except that the key is the integer value P3, not the value of the integer stored in register P3.
                            Mem data = mems[op.P2]; // MEM cell holding data for the record to be inserted
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            Debug.Assert(E.MemIsValid(data));
                            VdbeCursor cur = Cursors[op.P1]; // Cursor to table into which insert is written
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.Cursor != null);
                            Debug.Assert(cur.PseudoTableReg == 0);
                            Debug.Assert(cur.IsTable);
                            REGISTER_TRACE(op.P2, data);

                            long keyId; // The integer ROWID or key for the record to be inserted
                            if (op.Opcode == OP.Insert)
                            {
                                Mem key = mems[op.P3]; // MEM cell holding key  for the record
                                Debug.Assert((key.Flags & MEM.Int) != 0);
                                Debug.Assert(E.MemIsValid(key));
                                REGISTER_TRACE(op.P3, key);
                                keyId = key.u.I;
                            }
                            else
                            {
                                Debug.Assert(op.Opcode == OP.InsertInt);
                                keyId = op.P3;
                            }

                            if (((OPFLAG)op.P5 & OPFLAG.NCHANGE) != 0) Changes++;
                            if (((OPFLAG)op.P5 & OPFLAG.LASTROWID) != 0) ctx.LastRowID = lastRowid = keyId;
                            if ((data.Flags & MEM.Null) != 0)
                            {
                                data.Z_ = null;
                                data.Z = null;
                                data.N = 0;
                            }
                            else
                                Debug.Assert((data.Flags & (MEM.Blob | MEM.Str)) != 0);
                            int seekResult = (((OPFLAG)op.P5 & OPFLAG.USESEEKRESULT) != 0 ? cur.SeekResult : 0); // Result of prior seek or 0 if no USESEEKRESULT flag
                            int zeros = ((data.Flags & MEM.Zero) != 0 ? data.u.Zeros : 0); // Number of zero-bytes to append
                            rc = Btree.Insert(cur.Cursor, null, keyId, data.Z_, data.N, zeros, ((OPFLAG)op.P5 & OPFLAG.APPEND) != 0 ? 1 : 0, seekResult);
                            cur.RowidIsValid = false;
                            cur.DeferredMoveto = false;
                            cur.CacheStatus = CACHE_STALE;

                            // Invoke the update-hook if required.
                            if (rc == RC.OK && ctx.UpdateCallback != null && op.P4.Z != null)
                            {
                                string dbName = ctx.DBs[cur.Db].Name; // database name - used by the update hook
                                string tableName = op.P4.Z; // Table name - used by the opdate hook
                                int op2 = (((OPFLAG)op.P5 & OPFLAG.ISUPDATE) != 0 ? AUTH.UPDATE : AUTH.INSERT); // Opcode for update hook: SQLITE_UPDATE or SQLITE_INSERT
                                Debug.Assert(cur.IsTable);
                                ctx.UpdateCallback(ctx.UpdateArg, op2, dbName, tableName, keyId);
                                Debug.Assert(cur.Db >= 0);
                            }
                            break;
                        }
                    case OP.Delete:
                        {
                            // Opcode: Delete P1 P2 * P4 *
                            //
                            // Delete the record at which the P1 cursor is currently pointing.
                            //
                            // The cursor will be left pointing at either the next or the previous record in the table. If it is left pointing at the next record, then
                            // the next Next instruction will be a no-op.  Hence it is OK to delete a record from within an Next loop.
                            //
                            // If the OPFLAG_NCHANGE flag of P2 is set, then the row change count is incremented (otherwise not).
                            //
                            // P1 must not be pseudo-table.  It has to be a real table with multiple rows.
                            //
                            // If P4 is not NULL, then it is the name of the table that P1 is pointing to.  The update hook will be invoked, if it exists.
                            // If P4 is not NULL then the P1 cursor must have been positioned using OP_NotFound prior to invoking this opcode.
                            long keyId = 0;
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.Cursor != null); // Only valid for real tables, no pseudotables

                            // If the update-hook will be invoked, set iKey to the rowid of the row being deleted.
                            if (ctx.UpdateCallback != null && op.P4.Z != null)
                            {
                                Debug.Assert(cur.IsTable);
                                Debug.Assert(cur.RowidIsValid); // lastRowid set by previous OP_NotFound
                                keyId = cur.LastRowid;
                            }

                            // The OP_Delete opcode always follows an OP_NotExists or OP_Last or OP_Column on the same table without any intervening operations that
                            // might move or invalidate the cursor.  Hence cursor cur is always pointing to the row to be deleted and the sqlite3VdbeCursorMoveto() operation
                            // below is always a no-op and cannot fail.  We will run it anyhow, though, to guard against future changes to the code generator.
                            Debug.Assert(!cur.DeferredMoveto);
                            rc = CursorMoveto(cur);
                            if (C._NEVER(rc != RC.OK)) goto abort_due_to_error;

                            Btree.SetCachedRowid(cur.Cursor, 0);
                            rc = Btree.Delete(cur.Cursor);
                            cur.CacheStatus = CACHE_STALE;

                            // Invoke the update-hook if required.
                            if (rc == RC.OK && ctx.UpdateCallback != null && op.P4.Z != null)
                            {
                                string dbName = ctx.DBs[cur.Db].Name;
                                string tableName = op.P4.Z;
                                ctx.UpdateCallback(ctx.UpdateArg, AUTH.DELETE, dbName, tableName, keyId);
                                Debug.Assert(cur.Db >= 0);
                            }
                            if (((OPFLAG)op.P2 & OPFLAG.NCHANGE) != 0) Changes++;
                            break;
                        }
                    case OP.ResetCount:
                        {
                            // Opcode: ResetCount * * * * *
                            //
                            // The value of the change counter is copied to the database handle change counter (returned by subsequent calls to sqlite3_changes()).
                            // Then the VMs internal change counter resets to 0. This is used by trigger programs.
                            SetChanges(ctx, Changes);
                            Changes = 0;
                            break;
                        }
                    case OP.SorterCompare:
                        {
                            // Opcode: SorterCompare P1 P2 P3
                            //
                            // P1 is a sorter cursor. This instruction compares the record blob in register P3 with the entry that the sorter cursor currently points to.
                            // If, excluding the rowid fields at the end, the two records are a match, fall through to the next instruction. Otherwise, jump to instruction P2.
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(IsSorter(cur));
                            in3 = mems[op.P3];
                            int res;
                            rc = SorterCompare(cur, in3, ref res);
                            if (res != 0)
                                pc = op.P2 - 1;
                            break;
                        };
                    case OP.SorterData:
                        {
                            // Opcode: SorterData P1 P2 * * *
                            //
                            // Write into register P2 the current sorter data for sorter cursor P1.
                            out_ = mems[op.P2];
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur.IsSorter);
                            rc = SorterRowkey(cur, out_);
                            break;
                        }
                    case OP.RowKey:
                    case OP.RowData:
                        {
                            // Opcode: RowData P1 P2 * * *
                            //
                            // Write into register P2 the complete row data for cursor P1. There is no interpretation of the data.  
                            // It is just copied onto the P2 register exactly as it is found in the database file.
                            //
                            // If the P1 cursor must be pointing to a valid row (not a NULL row) of a real table, not a pseudo-table.
                            //
                            // Opcode: RowKey P1 P2 * * *
                            //
                            // Write into register P2 the complete row key for cursor P1. There is no interpretation of the data.  
                            // The key is copied onto the P3 register exactly as it is found in the database file.
                            //
                            // If the P1 cursor must be pointing to a valid row (not a NULL row) of a real table, not a pseudo-table.
                            out_ = mems[op.P2];
                            MemAboutToChange(this, out_);

                            // Note that RowKey and RowData are really exactly the same instruction
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(!cur.IsSorter);
                            Debug.Assert(cur.IsTable || op.Opcode == OP.RowKey);
                            Debug.Assert(cur.IsIndex || op.Opcode == OP.RowData);
                            Debug.Assert(cur != null);
                            Debug.Assert(!cur.NullRow);
                            Debug.Assert(cur.PseudoTableReg == false);
                            Debug.Assert(cur.Cursor != null);
                            Btree.BtCursor crsr = cur.Cursor;
                            Debug.Assert(Btree.CursorIsValid(crsr));

                            // The OP_RowKey and OP_RowData opcodes always follow OP_NotExists or OP_Rewind/Op_Next with no intervening instructions that might invalidate
                            // the cursor.  Hence the following sqlite3VdbeCursorMoveto() call is always a no-op and can never fail.  But we leave it in place as a safety.
                            Debug.Assert(!cur.DeferredMoveto);
                            rc = CursorMoveto(cur);
                            if (C._NEVER(rc != RC.OK)) goto abort_due_to_error;

                            uint n = 0;
                            long n64 = 0;
                            if (cur.IsIndex)
                            {
                                Debug.Assert(!cur.IsTable);
                                rc = Btree.KeySize(crsr, ref n64);
                                Debug.Assert(rc == RC.OK); // True because of CursorMoveto() call above
                                if (n64 > ctx.Limits[(int)LIMIT.LENGTH])
                                    goto too_big;
                                n = (uint)n64;
                            }
                            else
                            {
                                rc = Btree.DataSize(crsr, ref n);
                                Debug.Assert(rc == RC.OK); // DataSize() cannot fail
                                if (n > (uint)ctx.Limits[(int)LIMIT.LENGTH])
                                    goto too_big;
                            }
                            if (MemGrow(out_, (int)n, false) != 0)
                                goto no_mem;
                            out_.N = (int)n;
                            E.MemSetTypeFlag(out_, MEM.Blob);
                            rc = (cur.IsIndex ? Btree.Key(crsr, 0, n, (out_.Z_ = C._alloc((int)n))) : Btree.Data(crsr, 0, (uint)n, (out_.Z_ = C._alloc((int)crsr.Info.Data))));
                            out_.Encode = TEXTENCODE.UTF8; // In case the blob is ever cast to text
                            UPDATE_MAX_BLOBSIZE(out_);
                            break;
                        }
                    case OP.Rowid: // out2-prerelease
                        {
                            // Opcode: Rowid P1 P2 * * *
                            //
                            // Store in register P2 an integer which is the key of the table entry that P1 is currently point to.
                            //
                            // P1 can be either an ordinary table or a virtual table.  There used to be a separate OP_VRowid opcode for use with virtual tables, but this
                            // one opcode now works for both table types.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.PseudoTableReg == 0 || cur.NullRow);
                            long v = 0;
                            if (cur.NullRow)
                            {
                                out_.Flags = MEM.Null;
                                break;
                            }
                            else if (cur.DeferredMoveto)
                            {
                                v = cur.MovetoTarget;
#if !OMIT_VIRTUALTABLE
                            }
                            else if (cur.VtabCursor != null)
                            {
                                IVTable vtable = cur.VtabCursor.IVTable;
                                ITableModule module = vtable.IModule;
                                Debug.Assert(module.Rowid != null);
                                rc = module.Rowid(cur.VtabCursor, out v);
                                ImportVtabErrMsg(this, vtable);
#endif
                            }
                            else
                            {
                                Debug.Assert(cur.Cursor != null);
                                rc = CursorMoveto(cur);
                                if (rc != 0) goto abort_due_to_error;
                                if (cur.RowidIsValid)
                                    v = cur.LastRowid;
                                else
                                {
                                    rc = Btree.KeySize(cur.Cursor, ref v);
                                    Debug.Assert(rc == RC.OK); // Always so because of CursorMoveto() abov
                                }
                            }
                            out_.u.I = (long)v;
                            break;
                        }
                    case OP.NullRow:
                        {
                            // Opcode: NullRow P1 * * * *
                            //
                            // Move the cursor P1 to a null row.  Any OP_Column operations that occur while the cursor is on the null row will always write a NULL.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            cur.NullRow = true;
                            cur.RowidIsValid = false;
                            if (cur.Cursor != null)
                                Btree.ClearCursor(cur.Cursor);
                            break;
                        }
                    case OP.Last: // jump
                        {
                            // Opcode: Last P1 P2 * * *
                            //
                            // The next use of the Rowid or Column or Next instruction for P1 will refer to the last entry in the database table or index.
                            // If the table or index is empty and P2>0, then jump immediately to P2. If P2 is 0 or if the table or index is not empty, fall through
                            // to the following instruction.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.IsSorter == (op.Opcode == OP.SorterSort));
                            Btree.BtCursor crsr = cur.Cursor;
                            int res = 0;
                            if (C._ALWAYS(crsr != null))
                                rc = Btree.Last(crsr, ref res);
                            cur.NullRow = (res == 1);
                            cur.DeferredMoveto = false;
                            cur.RowidIsValid = false;
                            cur.CacheStatus = CACHE_STALE;
                            if (op.P2 > 0 && res != 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.SorterSort: // jump
                    case OP.Sort: // jump
                        {
                            // Opcode: Sort P1 P2 * * *
                            //
                            // This opcode does exactly the same thing as OP_Rewind except that it increments an undocumented global variable used for testing.
                            //
                            // Sorting is accomplished by writing records into a sorting index, then rewinding that index and playing it back from beginning to
                            // end.  We use the OP_Sort opcode instead of OP_Rewind to do the rewinding so that the global variable will be incremented and
                            // regression tests can determine whether or not the optimizer is correctly optimizing out sorts.
#if TEST
                            g_sort_count++;
                            g_search_count--;
#endif
                            Counters[(int)STMTSTATUS.SORT - 1]++;
                            // Fall through into OP_Rewind
                            goto case OP.Rewind;
                        }
                    case OP.Rewind: // jump
                        {
                            // Opcode: Rewind P1 P2 * * *
                            //
                            // The next use of the Rowid or Column or Next instruction for P1 will refer to the first entry in the database table or index.
                            // If the table or index is empty and P2>0, then jump immediately to P2. If P2 is 0 or if the table or index is not empty, fall through
                            // to the following instruction.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            int res = 1;
                            if (IsSorter(cur))
                                rc = SorterRewind(ctx, cur, ref res);
                            else
                            {
                                Btree.BtCursor crsr = cur.Cursor;
                                Debug.Assert(crsr != null);
                                rc = Btree.First(crsr, ref res);
                                cur.AtFirst = (res == 0);
                                cur.DeferredMoveto = false;
                                cur.CacheStatus = CACHE_STALE;
                                cur.RowidIsValid = false;
                            }
                            cur.NullRow = (res != 0);
                            Debug.Assert(op.P2 > 0 && op.P2 < Ops.length);
                            if (res != 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.SorterNext: // jump
                    case OP.Prev: // jump
                    case OP.Next: // jump
                        {
                            // Opcode: Next P1 P2 * P4 P5
                            //
                            // Advance cursor P1 so that it points to the next key/data pair in its table or index.  If there are no more key/value pairs then fall through
                            // to the following instruction.  But if the cursor advance was successful, jump immediately to P2.
                            //
                            // The P1 cursor must be for a real table, not a pseudo-table.
                            //
                            // P4 is always of type P4T_ADVANCE. The function pointer points to sqlite3BtreeNext().
                            //
                            // If P5 is positive and the jump is taken, then event counter number P5-1 in the prepared statement is incremented.
                            //
                            // See also: Prev
                            //
                            // Opcode: Prev P1 P2 * * P5
                            //
                            // Back up cursor P1 so that it points to the previous key/data pair in its table or index.  If there is no previous key/value pairs then fall through
                            // to the following instruction.  But if the cursor backup was successful, jump immediately to P2.
                            //
                            // The P1 cursor must be for a real table, not a pseudo-table.
                            //
                            // P4 is always of type P4T_ADVANCE. The function pointer points to sqlite3BtreePrevious().
                            //
                            // If P5 is positive and the jump is taken, then event counter number P5-1 in the prepared statement is incremented.
                            CHECK_FOR_INTERRUPT;
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            Debug.Assert(op.P5 <= Counters.Length);
                            VdbeCursor cur = Cursors[op.P1];
                            if (cur == null)
                                break; // See ticket #2273
                            Debug.Assert(cur.IsSorter == (op.Opcode == OP.SorterNext));
                            int res;
                            if (IsSorter(cur))
                            {
                                Debug.Assert(op.Opcode == OP.SorterNext);
                                rc = SorterNext(ctx, cur, ref res);
                            }
                            else
                            {
                                res = 1;
                                Debug.Assert(!cur.DeferredMoveto);
                                Debug.Assert(cur.Cursor != null);
                                Debug.Assert(op.Opcode != OP.Next || op.P4.Advance == Btree.Next_);
                                Debug.Assert(op.Opcode != OP.Prev || op.P4.Advance == Btree.Previous);
                                rc = op.P4.Advance(cur.Cursor, res);
                            }
                            cur.NullRow = (res != 0);
                            cur.CacheStatus = CACHE_STALE;
                            if (res == 0)
                            {
                                pc = op.P2 - 1;
                                if (op.P5) Counters[op.P5 - 1]++;
#if TEST
                                g_search_count++;
#endif
                            }
                            cur.RowidIsValid = false;
                            break;
                        }
                    #region Index
                    case OP.SorterInsert: // in2
                    case OP.IdxInsert: // in2
                        {
                            // Opcode: IdxInsert P1 P2 P3 * P5
                            //
                            // Register P2 holds an SQL index key made using the MakeRecord instructions.  This opcode writes that key
                            // into the index P1.  Data for the entry is nil.
                            //
                            // P3 is a flag that provides a hint to the b-tree layer that this insert is likely to be an append.
                            //
                            // This instruction only works for indices.  The equivalent instruction for tables is OP_Insert.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.IsSorter == (op.Opcode == OP.SorterInsert));
                            in2 = mems[op.P2];
                            Debug.Assert((in2.Flags & MEM.Blob) != 0);
                            BtCursor crsr = cur.Cursor;
                            if (C._ALWAYS(crsr != null))
                            {
                                Debug.Assert(!cur.IsTable);
                                ExpandBlob(in2);
                                if (rc == RC.OK)
                                {
                                    if (IsSorter(cur))
                                        rc = SorterWrite(ctx, cur, in2);
                                    else
                                    {
                                        int keyLength = in2.N;
                                        byte[] key = ((in2.Flags & MEM.Blob) != 0 ? in2.Z_ : Encoding.UTF8.GetBytes(in2.Z));
                                        rc = Btree.Insert(crsr, key, keyLength, null, 0, 0, (op.P3 != 0 ? 1 : 0), (((OPFLAG)op.P5 & OPFLAG.USESEEKRESULT) != 0 ? cur.SeekResult : 0));
                                        Debug.Assert(!cur.DeferredMoveto);
                                        cur.CacheStatus = CACHE_STALE;
                                    }
                                }
                            }
                            break;
                        }
                    case OP.IdxDelete:
                        {
                            // Opcode: IdxDelete P1 P2 P3 * *
                            //
                            // The content of P3 registers starting at register P2 form an unpacked index key. This opcode removes that entry from the 
                            // index opened by cursor P1.
                            Debug.Assert(op.P3 > 0);
                            Debug.Assert(op.P2 > 0 && op.P2 + op.P3 <= Mems.length + 1);
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = p.apCsr[op.P1];
                            Debug.Assert(cur != null);
                            BtCursor crsr = cur.Cursor;
                            if (C._ALWAYS(crsr != null))
                            {

                                UnpackedRecord r = new UnpackedRecord();
                                r.KeyInfo = cur.KeyInfo;
                                r.Fields = (ushort)op.P3;
                                r.Flags = 0;
                                r.Mems = new Mem[r.Fields];
                                for (int ra = 0; ra < r.Fields; ra++)
                                {
                                    r.Mems[ra] = mems[op.P2 + ra];
#if DEBUG
                                    Debug.Assert(MemIsValid(r.Mems[ra]));
#endif
                                }
                                int res = 0;
                                rc = Btree.MovetoUnpacked(crsr, r, 0, 0, ref res);
                                if (rc == RC.OK && res == 0)
                                    rc = Btree.Delete(crsr);
                                Debug.Assert(!cur.DeferredMoveto);
                                cur.CacheStatus = CACHE_STALE;
                            }
                            break;
                        }
                    case OP.IdxRowid: // out2-prerelease
                        {
                            // Opcode: IdxRowid P1 P2 * * *
                            //
                            // Write into register P2 an integer which is the last entry in the record at the end of the index key pointed to by cursor P1.  This integer should be
                            // the rowid of the table entry to which this index entry points.
                            //
                            // See also: Rowid, MakeRecord.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            BtCursor crsr = cur.Cursor;
                            out_.Flags = MEM.Null;
                            if (C._ALWAYS(crsr != null))
                            {
                                rc = Vdbe.CursorMoveto(cur);
                                if (C._NEVER(rc != 0)) goto abort_due_to_error;
                                Debug.Assert(!cur.DeferredMoveto);
                                Debug.Assert(!cur.IsTable);
                                if (!cur.NullRow)
                                {
                                    long rowid = 0;
                                    rc = IdxRowid(ctx, crsr, ref rowid);
                                    if (rc != RC.OK)
                                        goto abort_due_to_error;
                                    out_.u.I = rowid;
                                    out_.Flags = MEM_Int;
                                }
                            }
                            break;
                        }
                    case OP.IdxLT: // jump
                    case OP.IdxGE: // jump
                        {
                            // Opcode: IdxGE P1 P2 P3 P4 P5
                            //
                            // The P4 register values beginning with P3 form an unpacked index key that omits the ROWID.  Compare this key value against the index 
                            // that P1 is currently pointing to, ignoring the ROWID on the P1 index.
                            //
                            // If the P1 index entry is greater than or equal to the key value then jump to P2.  Otherwise fall through to the next instruction.
                            //
                            // If P5 is non-zero then the key value is increased by an epsilon prior to the comparison.  This make the opcode work like IdxGT except
                            // that if the key from register P3 is a prefix of the key in the cursor, the result is false whereas it would be true with IdxGT.
                            //
                            // Opcode: IdxLT P1 P2 P3 P4 P5
                            //
                            // The P4 register values beginning with P3 form an unpacked index key that omits the ROWID.  Compare this key value against the index 
                            // that P1 is currently pointing to, ignoring the ROWID on the P1 index.
                            //
                            // If the P1 index entry is less than the key value then jump to P2. Otherwise fall through to the next instruction.
                            //
                            // If P5 is non-zero then the key value is increased by an epsilon prior to the comparison.  This makes the opcode work like IdxLE.
                            Debug.Assert(op.P1 >= 0 && op.P1 < Cursors.length);
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur != null);
                            Debug.Assert(cur.IsOrdered);
                            if (C._ALWAYS(cur.Cursor != null))
                            {
                                Debug.Assert(!cur.DeferredMoveto);
                                Debug.Assert(op.P5 == 0 || op.P5 == 1);
                                Debug.Assert(op.P4Type == P4T.INT32);
                                UnpackedRecord r = new UnpackedRecord();
                                r.KeyInfo = cur.KeyInfo;
                                r.Fields = (ushort)op.P4.I;
                                r.Flags = (op.P5 != 0 ? UNPACKED.INCRKEY | UNPACKED.IGNORE_ROWID : UNPACKED.IGNORE_ROWID);
                                r.Mems = new Mem[r.Fields];
                                for (int i = 0; i < r.Fields; i++)
                                {
                                    r.Mems[i] = mems[op.P3 + i]; //: r.Mems = mems[op.P3];
#if DEBUG
                                    Debug.Assert(MemIsValid(r.Mems[i]));
#endif
                                }
                                int res = 0;
                                rc = IdxKeyCompare(cur, r, ref res);
                                if (op.Opcode == OP.IdxLT)
                                    res = -res;
                                else
                                {
                                    Debug.Assert(op.Opcode == OP.IdxGE);
                                    res++;
                                }
                                if (res > 0)
                                    pc = op.P2 - 1;
                            }
                            break;
                        }
                    #endregion
                    case OP.Destroy: // out2-prerelease
                        {
                            // Opcode: Destroy P1 P2 P3 * *
                            //
                            // Delete an entire database table or index whose root page in the database file is given by P1.
                            //
                            // The table being destroyed is in the main database file if P3==0.  If P3==1 then the table to be clear is in the auxiliary database file
                            // that is used to store tables create using CREATE TEMPORARY TABLE.
                            //
                            // If AUTOVACUUM is enabled then it is possible that another root page might be moved into the newly deleted root page in order to keep all
                            // root pages contiguous at the beginning of the database.  The former value of the root page that moved - its value before the move occurred -
                            // is stored in register P2.  If no page movement was required (because the table being dropped was already 
                            // the last one in the database) then a zero is stored in register P2. If AUTOVACUUM is disabled then a zero is stored in register P2.
                            //
                            // See also: Clear
                            int cnt;
#if !OMIT_VIRTUALTABLE
                            cnt = 0;
                            for (Vdbe v = ctx.Vdbes; v != null; v = v.Next)
                                if (v.magic == VDBE_MAGIC_RUN && v.inVtabMethod < 2 && v.pc >= 0)
                                    cnt++;
#else
                            cnt = ctx.ActiveVdbeCnt;
#endif
                            out_.Flags = MEM.Null;
                            if (cnt > 1)
                            {
                                rc = RC.LOCKED;
                                ErrorAction = OE.Abort;
                            }
                            else
                            {
                                int db = op.P3;
                                Debug.Assert(cnt == 1);
                                Debug.Assert((BtreeMask & (((yDbMask)1) << db)) != 0);
                                int moved = 0;
                                rc = ctx.DBs[db].Bt.DropTable(op.P1, ref moved);
                                out_.Flags = MEM.Int;
                                out_.u.I = moved;
#if !OMIT_AUTOVACUUM
                                if (rc == RC.OK && moved != 0)
                                {
                                    Parse.RootPageMoved(ctx, db, moved, op.P1);
                                    // All OP_Destroy operations occur on the same btree
                                    Debug.Assert(resetSchemaOnFault == 0 || resetSchemaOnFault == db + 1);
                                    resetSchemaOnFault = (byte)(db + 1);
                                }
#endif
                            }
                            break;
                        }
                    case OP.Clear:
                        {
                            // Opcode: Clear P1 P2 P3
                            //
                            // Delete all contents of the database table or index whose root page in the database file is given by P1.  But, unlike Destroy, do not
                            // remove the table or index from the database file.
                            //
                            // The table being clear is in the main database file if P2==0.  If P2==1 then the table to be clear is in the auxiliary database file
                            // that is used to store tables create using CREATE TEMPORARY TABLE.
                            //
                            // If the P3 value is non-zero, then the table referred to must be an intkey table (an SQL table, not an index). In this case the row change 
                            // count is incremented by the number of rows in the table being cleared. If P3 is greater than zero, then the value stored in register P3 is
                            // also incremented by the number of rows in the table being cleared.
                            //
                            // See also: Destroy
                            int changes = 0;
                            Debug.Assert((BtreeMask & (((yDbMask)1) << op.P2)) != 0);
                            int dummy1 = 0;
                            rc = (op.P3 != 0 ? ctx.DBs[op.P2].Bt.ClearTable(op.P1, ref changes) : ctx.DBs[op.P2].Bt.ClearTable(op.P1, ref dummy1));
                            if (op.P3 != 0)
                            {
                                Changes += changes;
                                if (op.P3 > 0)
                                {
                                    Debug.Assert(E.MemIsValid(mems[op.P3]));
                                    MemAboutToChange(this, mems[op.P3]);
                                    mems[op.P3].u.I += changes;
                                }
                            }
                            break;
                        }
                    case OP.CreateIndex: // out2-prerelease
                    case OP.CreateTable: // out2-prerelease
                        {
                            // Opcode: CreateTable P1 P2 * * *
                            //
                            // Allocate a new table in the main database file if P1==0 or in the auxiliary database file if P1==1 or in an attached database if
                            // P1>1.  Write the root page number of the new table into register P2
                            //
                            // The difference between a table and an index is this:  A table must have a 4-byte integer key and can have arbitrary data.  An index
                            // has an arbitrary key but no data.
                            //
                            // See also: CreateIndex
                            //
                            // Opcode: CreateIndex P1 P2 * * *
                            //
                            // Allocate a new index in the main database file if P1==0 or in the auxiliary database file if P1==1 or in an attached database if
                            // P1>1.  Write the root page number of the new table into register P2.
                            //
                            // See documentation on OP_CreateTable for additional information.
                            int pgid = 0;
                            Debug.Assert(op.P1 >= 0 && op.P1 < ctx.nDb);
                            Debug.Assert((BtreeMask & (((yDbMask)1) << op.P1)) != 0);
                            Context.DB db = ctx.DBs[op.P1];
                            Debug.Assert(db.Bt != null);
                            int flags = (op.opcode == OP.CreateTable ? BTREE_INTKEY : BTREE_BLOBKEY);
                            rc = db.Bt.CreateTable(ref pgid, flags);
                            out_.u.I = pgid;
                            break;
                        }
                    case OP.ParseSchema:
                        {
                            // Opcode: ParseSchema P1 * * P4 *
                            //
                            // Read and parse all entries from the SQLITE_MASTER table of database P1 that match the WHERE clause P4. 
                            //
                            // This opcode invokes the parser to create a new virtual machine, then runs the new virtual machine.  It is thus a re-entrant opcode.
#if DEBUG
                            // Any prepared statement that invokes this opcode will hold mutexes on every btree.  This is a prerequisite for invoking sqlite3InitCallback().
                            for (db = 0; db < ctx.DBs.length; db++)
                                Debug.Assert(db == 1 || ctx.DBs[db].Bt.HoldsMutex());
#endif
                            db = op.P1;
                            Debug.Assert(db >= 0 && db < ctx.DBs.length);
                            Debug.Assert(E.DbHasProperty(ctx, db, SCHEMA.SchemaLoaded));
                            // Used to be a conditional
                            {
                                masterName = E.SCHEMA_TABLE(db);
                                InitData initData = new InitData();
                                initData.Ctx = ctx;
                                initData.Db = op.P1;
                                initData.ErrMsg = ErrMsg;
                                string sql = C._mtagprintf(ctx, "SELECT name, rootpage, sql FROM '%q'.%s WHERE %s ORDER BY rowid", ctx.DBs[db].Name, masterName, op.P4.Z);
                                if (sql == null)
                                    rc = RC.NOMEM;
                                else
                                {
                                    Debug.Assert(!ctx.Init.Busy);
                                    ctx.Init.Busy = true;
                                    initData.RC = RC.OK;
                                    //Debug.Assert( 0 == db.mallocFailed );
                                    rc = sqlite3_exec(ctx, sql, Prepare.InitCallback, (object)initData, 0);
                                    if (rc == RC.OK)
                                        rc = initData.RC;
                                    C._tagfree(ctx, ref sql);
                                    ctx.Init.Busy = false;
                                }
                            }
                            if (rc != 0) Parse.ResetAllSchemasOfConnection(ctx);
                            if (rc == RC.NOMEM)
                                goto no_mem;
                            break;
                        }

#if  !OMIT_ANALYZE
                    case OP.LoadAnalysis:
                        {
                            // Opcode: LoadAnalysis P1 * * * *
                            //
                            // Read the sqlite_stat1 table for database P1 and load the content of that table into the internal index hash table.  This will cause
                            // the analysis to be used when preparing all subsequent queries.
                            Debug.Assert(op.P1 >= 0 && op.P1 < ctx.DBs.length);
                            rc = Analyze.AnalysisLoad(ctx, op.P1);
                            break;
                        }
#endif
                    case OP.DropTable:
                        {
                            // Opcode: DropTable P1 * * P4 *
                            //
                            // Remove the internal (in-memory) data structures that describe the table named P4 in database P1.  This is called after a table
                            // is dropped in order to keep the internal representation of the schema consistent with what is on disk.
                            Parse.UnlinkAndDeleteTable(ctx, op.P1, op.P4.Z);
                            break;
                        }
                    case OP.DropIndex:
                        {
                            // Opcode: DropIndex P1 * * P4 *
                            //
                            // Remove the internal (in-memory) data structures that describe the index named P4 in database P1.  This is called after an index
                            // is dropped in order to keep the internal representation of the schema consistent with what is on disk.
                            Parse.UnlinkAndDeleteIndex(ctx, op.P1, op.P4.Z);
                            break;
                        }
                    case OP.DropTrigger:
                        {
                            // Opcode: DropTrigger P1 * * P4 *
                            //
                            // Remove the internal (in-memory) data structures that describe the trigger named P4 in database P1.  This is called after a trigger
                            // is dropped in order to keep the internal representation of the schema consistent with what is on disk.
                            Trigger.UnlinkAndDeleteTrigger(ctx, op.P1, op.P4.Z);
                            break;
                        }
#if !OMIT_INTEGRITY_CHECK
                    case OP.IntegrityCk:
                        {
                            // Opcode: IntegrityCk P1 P2 P3 * P5
                            //
                            // Do an analysis of the currently open database.  Store in register P1 the text of an error message describing any problems.
                            // If no problems are found, store a NULL in register P1.
                            //
                            // The register P3 contains the maximum number of allowed errors. At most reg(P3) errors will be reported.
                            // In other words, the analysis stops as soon as reg(P1) errors are seen.  Reg(P1) is updated with the number of errors remaining.
                            //
                            // The root page numbers of all tables in the database are integer stored in reg(P1), reg(P1+1), reg(P1+2), ....  There are P2 tables total.
                            //
                            // If P5 is not zero, the check is done on the auxiliary database file, not the main database file.
                            //
                            // This opcode is used to implement the integrity_check pragma.
                            int rootsLength = op.P2; // Number of tables to check.  (Number of root pages.)
                            Debug.Assert(rootsLength > 0);
                            Pid[] roots = (Pid[])C._alloc(roots, (rootsLength + 1));
                            if (roots == null) goto no_mem;
                            Debug.Assert(op.P3 > 0 && op.P3 <= Mems.length);
                            Mem err = mems[op.P3]; // Register keeping track of errors remaining
                            Debug.Assert((err.Flags & MEM.Int) != 0);
                            Debug.Assert((err.Flags & (MEM.Str | MEM.Blob)) == 0);
                            in1 = mems[op.P1];
                            int j;
                            for (j = 0; j < rootsLength; j++)
                                roots[j] = (int)IntValue(mems[op.P1 + j]); //: in1[j]);
                            roots[j] = 0;
                            Debug.Assert(op.P5 < ctx.nDb);
                            Debug.Assert((p.btreeMask & (((yDbMask)1) << op.P5)) != 0);
                            int errs = 0; // Number of errors reported
                            string z = ctx.DBs[op.P5].Bt.IntegrityCheck(roots, rootsLength, (int)err.u.i, ref errs); // Text of the error report
                            C._tagfree(ctx, ref roots);
                            err.u.I -= errs;
                            MemSetNull(in1);
                            if (errs == 0)
                                Debug.Assert(z == null);
                            else if (z == null)
                                goto no_mem;
                            else
                                MemSetStr(in1, z, -1, TEXTENCODE.UTF8, null);
                            UPDATE_MAX_BLOBSIZE(in1);
                            ChangeEncoding(in1, encoding);
                            break;
                        }
#endif
                    case OP.RowSetAdd: // in1, in2
                        {
                            // Opcode: RowSetAdd P1 P2 * * *
                            //
                            // Insert the integer value held by register P2 into a boolean index held in register P1.
                            //
                            // An assertion fails if P2 is not an integer.
                            in1 = mems[op.P1];
                            in2 = mems[op.P2];
                            Debug.Assert((in2.Flags & MEM.Int) != 0);
                            if ((in1.Flags & MEM.RowSet) == 0)
                            {
                                MemSetRowSet(in1);
                                if ((in1.Flags & MEM.RowSet) == 0) goto no_mem;
                            }
                            sqlite3RowSetInsert(in1.u.RowSet, in2.u.I);
                            break;
                        }
                    case OP.RowSetRead: // jump, in1, ref3
                        {
                            // Opcode: RowSetRead P1 P2 P3 * *
                            //
                            // Extract the smallest value from boolean index P1 and put that value into register P3.  Or, if boolean index P1 is initially empty, leave P3
                            // unchanged and jump to instruction P2.
                            CHECK_FOR_INTERRUPT;
                            in1 = mems[op.P1];
                            long val = 0;
                            if ((in1.Flags & MEM.RowSet) == 0 || sqlite3RowSetNext(in1.u.RowSet, ref val) == 0)
                            {
                                MemSetNull(in1); // The boolean index is empty
                                pc = op.P2 - 1;
                            }
                            else
                                MemSetInt64(mems[op.P3], val); // A value was pulled from the index
                            break;
                        }
                    case OP.RowSetTest: // jump, in1, in3
                        {
                            // Opcode: RowSetTest P1 P2 P3 P4
                            //
                            // Register P3 is assumed to hold a 64-bit integer value. If register P1 contains a RowSet object and that RowSet object contains
                            // the value held in P3, jump to register P2. Otherwise, insert the integer in P3 into the RowSet and continue on to the next opcode.
                            //
                            // The RowSet object is optimized for the case where successive sets of integers, where each set contains no duplicates. Each set
                            // of values is identified by a unique P4 value. The first set must have P4==0, the final set P4=-1.  P4 must be either -1 or
                            // non-negative.  For non-negative values of P4 only the lower 4 bits are significant.
                            //
                            // This allows optimizations: (a) when P4==0 there is no need to test the rowset object for P3, as it is guaranteed not to contain it,
                            // (b) when P4==-1 there is no need to insert the value, as it will never be tested for, and (c) when a value that is part of set X is
                            // inserted, there is no need to search to see if the same value was previously inserted as part of set X (only if it was previously
                            // inserted as part of some other set).
                            in1 = mems[op.P1];
                            in3 = mems[op.P3];
                            int set = op.P4.I;
                            Debug.Assert((in3.Flags & MEM.Int) != 0);
                            // If there is anything other than a rowset object in memory cell P1, delete it now and initialize P1 with an empty rowset
                            if ((in1.Flags & MEM.RowSet) == 0)
                            {
                                MemSetRowSet(in1);
                                if ((in1.Flags & MEM.RowSet) == 0) goto no_mem;
                            }
                            Debug.Assert(op.P4Type == P4T.INT32);
                            Debug.Assert(set == -1 || set >= 0);
                            if (set != 0)
                            {
                                int exists = sqlite3RowSetTest(in1.u.RowSet, (byte)(set >= 0 ? set & 0xf : 0xff), in3.u.I);
                                if (exists != 0)
                                {
                                    pc = op.P2 - 1;
                                    break;
                                }
                            }
                            if (set >= 0)
                                sqlite3RowSetInsert(in1.u.RowSet, in3.u.I);
                            break;
                        }
#if !OMIT_TRIGGER
                    case OP.Program: // jump
                        {
                            // Opcode: Program P1 P2 P3 P4 *
                            //
                            // Execute the trigger program passed as P4 (type P4T_SUBPROGRAM). 
                            //
                            // P1 contains the address of the memory cell that contains the first memory cell in an array of values used as arguments to the sub-program. P2 
                            // contains the address to jump to if the sub-program throws an IGNORE exception using the RAISE() function. Register P3 contains the address 
                            // of a memory cell in this (the parent) VM that is used to allocate the memory required by the sub-vdbe at runtime.
                            //
                            // P4 is a pointer to the VM containing the trigger program.
                            SubProgram program = op.P4.Program; // Sub-program to execute
                            Mem rt = memsLength[op.P3]; // Register to allocate runtime space
                            Debug.Assert(program.Ops.length > 0);

                            // If the p5 flag is clear, then recursive invocation of triggers is disabled for backwards compatibility (p5 is set if this sub-program
                            // is really a trigger, not a foreign key action, and the flag set and cleared by the "PRAGMA recursive_triggers" command is clear).
                            // 
                            // It is recursive invocation of triggers, at the SQL level, that is disabled. In some cases a single trigger may generate more than one 
                            // SubProgram (if the trigger may be executed with more than one different ON CONFLICT algorithm). SubProgram structures associated with a
                            // single trigger all have the same value for the SubProgram.token variable.
                            VdbeFrame frame; // New vdbe frame to execute in
                            if (op.P5 != 0)
                            {
                                int t = program.Token; // Token identifying trigger
                                for (frame = Frames; frame != null && frame.Token != t; frame = frame.Parent) ;
                                if (frame != null) break;
                            }

                            if (FramesLength >= ctx.Limits[(int)LIMIT.TRIGGER_DEPTH])
                            {
                                rc = RC.ERROR;
                                C._setstring(ref ErrMsg, ctx, "too many levels of trigger recursion");
                                break;
                            }

                            // Register pRt is used to store the memory required to save the state of the current program, and the memory required at runtime to execute
                            // the trigger program. If this trigger has been fired before, then pRt is already allocated. Otherwise, it must be initialized.  */
                            int childMems; // Number of memory registers for sub-program
                            if ((rt.Flags & MEM.Frame) == 0)
                            {
                                // SubProgram.nMem is set to the number of memory cells used by the program stored in SubProgram.ops. As well as these, one memory
                                // cell is required for each cursor used by the program. Set local variable nMem (and later, VdbeFrame.nChildMem) to this value.
                                childMems = program.Mems + program.Csrs;
                                //int byte = ROUND8(sizeof(VdbeFrame))
                                //+ childMems * sizeof(Mem)
                                //+ program.nCsr * sizeof(VdbeCursor); // Bytes of runtime space required for sub-program
                                frame = new VdbeFrame();
                                if (!frame)
                                    goto no_mem;
                                MemRelease(rt);
                                rt.Flags = MEM.Frame;
                                rt.u.Frame = frame;

                                frame.V = this;
                                frame.ChildMems = childMems;
                                frame.ChildCursors = program.Csrs;
                                frame.PC = pc;
                                frame.Mems.data = Mems.data;
                                frame.Mems.length = Mems.length;
                                frame.Cursors.data = Cursors.data;
                                frame.Cursors.length = Cursors.length;
                                frame.Ops.data = Ops.data;
                                frame.Ops.length = Ops.length;
                                frame.Token = program.Token;
                                frame.OnceFlags.data = OnceFlags.data;
                                frame.OnceFlags.length = OnceFlags.length;

                                //: C#
                                Mem mem = null; // Used to iterate through memory cells
                                //: childMems is 1 based, so allocate 1 extra cell under C#
                                frame._ChildMems = new Mem[frame.ChildMems + 1];
                                for (int i = 0; i < frame._ChildMems.Length; i++) //: mem = VdbeFrameMem(frame ); mem != end; mem++)
                                {
                                    frame._ChildMems[i] = mem = C._alloc(mem);
                                    mem.Flags = MEM.Invalid;
                                    mem.Ctx = ctx;
                                }
                                frame._ChildCursors = new VdbeCursor[frame.ChildCursors];
                                for (int i = 0; i < frame.ChildCursors; i++)
                                    frame._ChildCursors[i] = new VdbeCursor();
                                frame._ChildOnceFlags = new byte[program.Onces];
                            }
                            else
                            {
                                frame = rt.u.Frame;
                                Debug.Assert(program.Mems + program.Csrs == frame.ChildMems);
                                Debug.Assert(program.Csrs == frame.ChildCursors);
                                Debug.Assert(pc == frame.PC);
                            }

                            FramesLength++;
                            frame.Parent = Frames;
                            frame.LastRowID = lastRowid;
                            frame.Changes = Changes;
                            Changes = 0;
                            Frames = frame;
                            Mems.data = mem = frame._ChildMems; //: &VdbeFrameMem(frame)[-1];
                            Mems.length = frame.ChildMems;
                            Cursors.length = (ushort)frame.ChildCursors;
                            Cursors.data = frame._ChildCursors; //: &mems[Mems.length+1];
                            Ops.data = ops = program.Ops.data;
                            Ops.length = program.Ops.length;
                            OnceFlags.data = frame._ChildOnceFlags; //: &Cursors[Cursors.length];
                            OnceFlags.length = program.Onces;
                            pc = -1;
                            break;
                        }
                    case OP.Param: // out2-prerelease
                        {
                            // Opcode: Param P1 P2 * * *
                            //
                            // This opcode is only ever present in sub-programs called via the OP_Program instruction. Copy a value currently stored in a memory 
                            // cell of the calling (parent) frame to cell P2 in the current frames address space. This is used by trigger programs to access the new.* 
                            // and old.* values.
                            //
                            // The address of the cell in the parent frame is determined by adding the value of the P1 argument to the value of the P1 argument to the
                            // calling OP_Program instruction.
                            VdbeFrame frame = Frames;
                            Mem in_ = frame.Mems[op.P1 + frame.Ops[frame.PC].P1];
                            MemShallowCopy(out_, in_, MEM_Ephem);
                            break;
                        }
#endif
#if !OMIT_FOREIGN_KEY
                    case OP.FkCounter:
                        {
                            // Opcode: FkCounter P1 P2 * * *
                            //
                            // Increment a "constraint counter" by P2 (P2 may be negative or positive). If P1 is non-zero, the database constraint counter is incremented 
                            // (deferred foreign key constraints). Otherwise, if P1 is zero, the statement counter is incremented (immediate foreign key constraints).
                            if (op.P1 != 0)
                                ctx.DeferredCons += op.P2;
                            else
                                FkConstraints += op.P2;
                            break;
                        }
                    case OP.FkIfZero: // jump
                        {
                            // Opcode: FkIfZero P1 P2 * * *
                            //
                            // This opcode tests if a foreign key constraint-counter is currently zero. If so, jump to instruction P2. Otherwise, fall through to the next instruction.
                            //
                            // If P1 is non-zero, then the jump is taken if the database constraint-counter is zero (the one that counts deferred constraint violations). If P1 is
                            // zero, the jump is taken if the statement constraint-counter is zero (immediate foreign key constraint violations).
                            if (op.P1 != 0)
                            {
                                if (ctx.DeferredCons == 0) pc = op.P2 - 1;
                            }
                            else
                            {
                                if (FkConstraints == 0) pc = op.P2 - 1;
                            }
                            break;
                        }
#endif
#if !OMIT_AUTOINCREMENT
                    case OP.MemMax: // in2
                        {
                            // Opcode: MemMax P1 P2 * * *
                            //
                            // P1 is a register in the root frame of this VM (the root frame is different from the current frame if this instruction is being executed
                            // within a sub-program). Set the value of register P1 to the maximum of its current value and the value in register P2.
                            //
                            // This instruction throws an error if the memory cell is not initially an integer.
                            Mem in1_;
                            VdbeFrame frame;
                            if (Frames != null)
                            {
                                for (frame = Frames; frame.Parent != null; frame = frame.Parent) ;
                                in1_ = frame.Mems[op.P1];
                            }
                            else
                                in1_ = mems[op.P1];
                            Debug.Assert(E.MemIsValid(in1_));
                            MemIntegerify(in1_);
                            in2 = mems[op.P2];
                            MemIntegerify(in2);
                            if (in1_.u.I < in2.u.I)
                                in1_.u.I = in2.u.I;
                            break;
                        }
#endif
                    case OP.IfPos: // jump, in1
                        {
                            // Opcode: IfPos P1 P2 * * *
                            //
                            // If the value of register P1 is 1 or greater, jump to P2.
                            //
                            // It is illegal to use this instruction on a register that does not contain an integer.  An assertion fault will result if you try.
                            in1 = mems[op.P1];
                            Debug.Assert((in1.Flags & MEM.Int) != 0);
                            if (in1.u.I > 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.IfNeg: // jump, in1
                        {
                            // Opcode: IfNeg P1 P2 * * *
                            //
                            // If the value of register P1 is less than zero, jump to P2. 
                            //
                            // It is illegal to use this instruction on a register that does not contain an integer.  An assertion fault will result if you try.
                            in1 = mems[op.P1];
                            Debug.Assert((in1.Flags & MEM.Int) != 0);
                            if (in1.u.I < 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.IfZero: // jump, in1
                        {
                            // Opcode: IfZero P1 P2 P3 * *
                            //
                            // The register P1 must contain an integer.  Add literal P3 to the value in register P1.  If the result is exactly 0, jump to P2. 
                            //
                            // It is illegal to use this instruction on a register that does not contain an integer.  An assertion fault will result if you try.
                            in1 = mems[op.P1];
                            Debug.Assert((in1.Flags & MEM.Int) != 0);
                            in1.u.I += op.P3;
                            if (in1.u.I == 0)
                                pc = op.P2 - 1;
                            break;
                        }
                    case OP.AggStep:
                        {
                            // Opcode: AggStep * P2 P3 P4 P5
                            //
                            // Execute the step function for an aggregate.  The function has P5 arguments.   P4 is a pointer to the FuncDef
                            // structure that specifies the function.  Use register P3 as the accumulator.
                            //
                            // The P5 arguments are taken from register P2 and its successors.
                            int n = op.P5;
                            Debug.Assert(n >= 0);
                            Mem[] vals = Args;
                            Debug.AssertMayAbort(vals != null || n == 0);
                            Mem rec; // = mems[op.P2];
                            int i;
                            for (i = 0; i < n; i++)
                            {
                                rec = mems[op.P2 + i];
                                Debug.Assert(E.MemIsValid(rec));
                                vals[i] = rec;
                                MemAboutToChange(this, rec);
                                MemStoreType(rec);
                            }
                            FuncContext fctx = new FuncContext();
                            fctx.Func = op.P4.Func;
                            Debug.Assert(op.P3 > 0 && op.P3 <= Mems.length);
                            Mem mem;
                            fctx.Mem = mem = mems[op.P3];
                            mem.N++;
                            fctx.S.Flags = MEM_Null;
                            fctx.S.Z = null;
                            //ctx.S.Malloc = null;
                            fctx.S.Del = null;
                            fctx.S.Ctx = ctx;
                            fctx.IsError = 0;
                            fctx.Coll = null;
                            fctx.SkipFlag = false;
                            if ((fctx.Func.Flags & FUNC.NEEDCOLL) != 0)
                            {
                                Debug.Assert(pc > 0); //: op > Ops.data
                                Debug.Assert(Ops[pc - 1].P4Type == P4T.COLLSEQ); //: op[-1]
                                Debug.Assert(Ops[pc - 1].Opcode == OP.CollSeq); //: op[-1]
                                fctx.Coll = Ops[pc - 1].P4.Coll; //: op[-1]
                            }
                            fctx.Func.Step(fctx, n, vals); // IMP: R-24505-23230
                            if (fctx.IsError != 0)
                            {
                                C._setstring(ref ErrMsg, fctx, Value_Text(fctx.S));
                                rc = fctx.IsError;
                            }
                            if (fctx.SkipFlag)
                            {
                                Debug.Assert(Ops[pc - 1].Opcode == OP.CollSeq); //: op[-1]
                                i = Ops[pc - 1].P1; //: op[-1]
                                if (i != 0) MemSetInt64(mems[i], 1);
                            }
                            MemRelease(fctx.S);
                            break;
                        }
                    case OP.AggFinal:
                        {
                            // Opcode: AggFinal P1 P2 * P4 *
                            //
                            // Execute the finalizer function for an aggregate.  P1 is the memory location that is the accumulator for the aggregate.
                            //
                            // P2 is the number of arguments that the step function takes and P4 is a pointer to the FuncDef for this function.  The P2
                            // argument is not used by this opcode.  It is only there to disambiguate functions that can take varying numbers of arguments.  The
                            // P4 argument is only needed for the degenerate case where the step function was not previously called.
                            Debug.Assert(op.P1 > 0 && op.P1 <= Mems.length);
                            Mem mem = mems[op.P1];
                            Debug.Assert((mem.Flags & ~(MEM.Null | MEM.Agg)) == 0);
                            rc = MemFinalize(mem, op.P4.Func);
                            mems[op.P1] = mem;
                            if (rc != 0)
                                C._setstring(ref ErrMsg, ctx, Value_Text(mem));
                            ChangeEncoding(mem, encoding);
                            UPDATE_MAX_BLOBSIZE(mem);
                            if (MemTooBig(mem))
                                goto too_big;
                            break;
                        }
#if !OMIT_WAL
                    case OP.Checkpoint:
                        {
                            // Opcode: Checkpoint P1 P2 P3 * *
                            //
                            // Checkpoint database P1. This is a no-op if P1 is not currently in WAL mode. Parameter P2 is one of SQLITE_CHECKPOINT_PASSIVE, FULL
                            // or RESTART.  Write 1 or 0 into mem[P3] if the checkpoint returns SQLITE_BUSY or not, respectively.  Write the number of pages in the
                            // WAL after the checkpoint into mem[P3+1] and the number of pages in the WAL that have been checkpointed after the checkpoint
                            // completes into mem[P3+2].  However on an error, mem[P3+1] and mem[P3+2] are initialized to -1.
                            int[] res = new int[3]; // Results
                            res[0] = 0;
                            res[1] = res[2] = -1;
                            Debug.Assert(op.P2 == IPager.CHECKPOINT.PASSIVE || op.P2 == IPager.CHECKPOINT.FULL || op.P2 == IPager.CHECKPOINT.RESTART);
                            rc = sqlite3Checkpoint(ctx, op.P1, op.P2, ref res[1], ref res[2]);
                            if (rc == RC.BUSY)
                            {
                                rc = RC.OK;
                                res[0] = 1;
                            }
                            int i;
                            Mem mem;
                            for (i = 0, mem = mems[op.P3]; i < 3; i++)
                            {
                                mem = mems[op.P3 + 1];
                                MemSetInt64(mem, (long)res[i]);
                            }
                            break;
                        }
#endif
#if !OMIT_PRAGMA
                    case OP.JournalMode: // out2-prerelease
                        {
                            // Opcode: JournalMode P1 P2 P3 * P5
                            //
                            // Change the journal mode of database P1 to P3. P3 must be one of the PAGER_JOURNALMODE_XXX values. If changing between the various rollback
                            // modes (delete, truncate, persist, off and memory), this is a simple operation. No IO is required.
                            //
                            // If changing into or out of WAL mode the procedure is more complicated.
                            //
                            // Write a string containing the final journal-mode to register P2.
                            IPager.JOURNALMODE newMode = op.P3; // New journal mode
                            Debug.Assert(newMode == IPager.JOURNALMODE.DELETE || newMode == IPager.JOURNALMODE.TRUNCATE || newMode == IPager.JOURNALMODE.PERSIST || newMode == IPager.JOURNALMODE.OFF || newMode == IPager.JOURNALMODE.JMEMORY || newMode == IPager.JOURNALMODE.WAL || newMode == IPager.JOURNALMODE.JQUERY);
                            Debug.Assert(op.P1 >= 0 && op.P1 < ctx.DBs.length);

                            Btree bt = ctx.DBs[op.P1].Bt; // Btree to change journal mode of
                            Pager pager = bt.get_Pager(); // Pager associated with pBt
                            IPager.JOURNALMODE oldMode = pager.GetJournalMode(); // The old journal mode
                            if (newMode == IPager.JOURNALMODE.JQUERY) newMode = oldMode;
                            if (!pager.OkToChangeJournalMode()) newMode = oldMode;

#if !OMIT_WAL
                            string filename = pager.get_Filename(true); // Name of database file for pPager

                            // Do not allow a transition to journal_mode=WAL for a database in temporary storage or if the VFS does not support shared memory 
                            if (newMode == IPager.JOURNALMODE.WAL && (filename[0] == 0 || !pager.WalSupported())) // Temp file || No shared-memory support
                                newMode = oldMode;

                            if ((newMode != oldMode) && (oldMode == IPager.JOURNALMODE.WAL || newMode == IPager.JOURNALMODE.WAL))
                            {
                                if (ctx.AutoCommit == 0 || ctx.ActiveVdbeCnt > 1)
                                {
                                    rc = RC.ERROR;
                                    C._setstring(&ErrMsg, ctx, "cannot change %s wal mode from within a transaction", (newMode == IPager.JOURNALMODE.WAL ? "into" : "out of"));
                                    break;
                                }
                                else
                                {
                                    if (oldMode == IPager.JOURNALMODE.WAL)
                                    {
                                        // If leaving WAL mode, close the log file. If successful, the call to PagerCloseWal() checkpoints and deletes the write-ahead-log 
                                        // file. An EXCLUSIVE lock may still be held on the database file after a successful return. 
                                        rc = pager.CloseWal();
                                        if (rc == RC.OK)
                                            pager.SetJournalMode(newMode);
                                    }
                                    else if (oldMode == IPager.JOURNALMODE.JMEMORY)
                                        pager.SetJournalMode(IPager.JOURNALMODE.OFF); // Cannot transition directly from MEMORY to WAL.  Use mode OFF as an intermediate

                                    // Open a transaction on the database file. Regardless of the journal mode, this transaction always uses a rollback journal.
                                    Debug.Assert(!bt.IsInTrans());
                                    if (rc == RC.OK)
                                        rc = bt.SetVersion(newMode == IPager.JOURNALMODE.WAL ? 2 : 1);
                                }
                            }
#endif

                            if (rc != 0)
                                newMode = oldMode;
                            newMode = pager.SetJournalMode(newMode);

                            out_ = mems[op.P2];
                            out_.Flags = MEM.Str | MEM.Static | MEM.Term;
                            out_.Z = Pragma.JournalModename(newMode);
                            out_.N = out_.Z.Length;
                            out_.Encode = TEXTENCODE.UTF8;
                            ChangeEncoding(out_, encoding);
                            break;
                        }
#endif
#if !OMIT_VACUUM && !OMIT_ATTACH
                    case OP.Vacuum:
                        {
                            // Opcode: Vacuum * * * * *
                            //
                            // Vacuum the entire database.  This opcode will cause other virtual machines to be created and run.  It may not be called from within a transaction.                         
                            rc = Vacuum.RunVacuum(ref ErrMsg, ctx);
                            break;
                        }
#endif
#if !OMIT_AUTOVACUUM
                    case OP.IncrVacuum: // jump
                        {
                            // Opcode: IncrVacuum P1 P2 * * *
                            //
                            // Perform a single step of the incremental vacuum procedure on the P1 database. If the vacuum has finished, jump to instruction
                            // P2. Otherwise, fall through to the next instruction.
                            Debug.Assert(op.P1 >= 0 && op.P1 < ctx.DBs.length);
                            Debug.Assert((BtreeMask & (((yDbMask)1) << op.P1)) != 0);
                            Btree bt = ctx.DBs[op.P1].Bt;
                            rc = bt.IncrVacuum();
                            if (rc == RC.DONE)
                            {
                                pc = op.P2 - 1;
                                rc = RC.OK;
                            }
                            break;
                        }
#endif
                    case OP.Expire:
                        {
                            // Opcode: Expire P1 * * * *
                            //
                            // Cause precompiled statements to become expired. An expired statement fails with an error code of SQLITE_SCHEMA if it is ever executed (via sqlite3_step()).
                            // 
                            // If P1 is 0, then all SQL statements become expired. If P1 is non-zero, then only the currently executing statement is affected. 
                            if (op.P1 == 0)
                                ExpirePreparedStatements(ctx);
                            else
                                Expired = true;
                            break;
                        }
#if !OMIT_SHARED_CACHE
                    case OP.TableLock:
                        {
                            // Opcode: TableLock P1 P2 P3 P4 *
                            //
                            // Obtain a lock on a particular table. This instruction is only used when the shared-cache feature is enabled. 
                            //
                            // P1 is the index of the database in sqlite3.aDb[] of the database on which the lock is acquired.  A readlock is obtained if P3==0 or
                            // a write lock if P3==1.
                            //
                            // P2 contains the root-page of the table to lock.
                            //
                            // P4 contains a pointer to the name of the table being locked. This is only used to generate an error message if the lock cannot be obtained.
                            bool isWriteLock = (op.P3 != 0);
                            if (isWriteLock || (ctx.flags & Context.FLAG.ReadUncommitted) == 0)
                            {
                                int p1 = op.P1;
                                Debug.Assert(p1 >= 0 && p1 < ctx.DBs.length);
                                Debug.Assert((BtreeMask & (((yDbMask)1) << p1)) != 0);
                                rc = ctx.DBs[p1].Bt.LockTable(op.P2, isWriteLock);
                                if ((rc & 0xFF) == RC.LOCKED)
                                {
                                    string z = op.P4.Z;
                                    C._setstring(ref ErrMsg, ctx, "database table is locked: ", z);
                                }
                            }
                            break;
                        }
#endif
                    #region Virtual Table
#if !OMIT_VIRTUALTABLE
                    case OP.VBegin:
                        {
                            // Opcode: VBegin * * * P4 *
                            //
                            // P4 may be a pointer to an sqlite3_vtab structure. If so, call the xBegin method for that table.
                            //
                            // Also, whether or not P4 is set, check that this is not being called from within a callback to a virtual table xSync() method. If it is, the error
                            // code will be set to SQLITE_LOCKED.
                            VTable vtable = op.P4.VTable;
                            rc = VTable.Begin(ctx, vtable);
                            if (vtable != null) ImportVtabErrMsg(this, vtable.IVTable);
                            break;
                        }
                    case OP.VCreate:
                        {
                            // Opcode: VCreate P1 * * P4 *
                            //
                            // P4 is the name of a virtual table in database P1. Call the xCreate method for that table.
                            rc = VTable.CallCreate(ctx, op.P1, op.P4.Z, ref ErrMsg);
                            break;
                        }
                    case OP.VDestroy:
                        {
                            // Opcode: VDestroy P1 * * P4 *
                            //
                            // P4 is the name of a virtual table in database P1.  Call the xDestroy method of that table.
                            InVtabMethod = 2;
                            rc = VTable.CallDestroy(ctx, op.P1, op.P4.Z);
                            InVtabMethod = 0;
                            break;
                        }
                    case OP.VOpen:
                        {
                            // Opcode: VOpen P1 * * P4 *
                            //
                            // P4 is a pointer to a virtual table object, an sqlite3_vtab structure. P1 is a cursor number.  This opcode opens a cursor to the virtual
                            // table and stores that cursor in P1.
                            IVTable vtable = op.P4.VTable.IVTable;
                            ITableModule module = (ITableModule)vtable.IModule;
                            Debug.Assert(vtable != null && module != null);
                            IVTableCursor vtabCursor;
                            rc = module.Open(vtable, out vtabCursor);
                            ImportVtabErrMsg(this, vtable);
                            if (rc == RC.OK)
                            {
                                // Initialize sqlite3_vtab_cursor base class
                                vtabCursor.IVTable = vtable;

                                // Initialise vdbe cursor object
                                VdbeCursor cur = AllocateCursor(this, op.P1, 0, -1, false);
                                if (cur != null)
                                {
                                    cur.VtabCursor = vtabCursor;
                                    cur.IModule = vtabCursor.IVTable.IModule;
                                }
                                else
                                {
                                    ctx.MallocFailed = true;
                                    module.Close(ref vtabCursor);
                                }
                            }
                            break;
                        }
                    case OP.VFilter: // jump
                        {
                            // Opcode: VFilter P1 P2 P3 P4 *
                            //
                            // P1 is a cursor opened using VOpen.  P2 is an address to jump to if the filtered result set is empty.
                            //
                            // P4 is either NULL or a string that was generated by the xBestIndex method of the module.  The interpretation of the P4 string is left
                            // to the module implementation.
                            //
                            // This opcode invokes the xFilter method on the virtual table specified by P1.  The integer query plan parameter to xFilter is stored in register
                            // P3. Register P3+1 stores the argc parameter to be passed to the xFilter method. Registers P3+2..P3+1+argc are the argc
                            // additional parameters which are passed to xFilter as argv. Register P3+2 becomes argv[0] when passed to xFilter.
                            //
                            // A jump is made to P2 if the result set after filtering would be empty.
                            int res;
                            Mem query = mems[op.P3];
                            Mem argc = mems[op.P3 + 1]; //: query[1];
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(E.MemIsValid(query));
                            REGISTER_TRACE(op.P3, query);
                            Debug.Assert(cur.VtabCursor != null);
                            IVTableCursor vtabCursor = cur.VtabCursor;
                            IVTable vtable = vtabCursor.IVTable;
                            ITableModule module = vtable.IModule;

                            // Grab the index number and argc parameters
                            Debug.Assert((query.Flags & MEM.Int) != 0 && argc.Flags == MEM.Int);
                            int argsLength = (int)argc.u.I;
                            int queryLength = (int)query.u.I;

                            // Invoke the xFilter method
                            {
                                res = 0;
                                Mem[] args = Args;
                                for (int i = 0; i < argsLength; i++)
                                {
                                    args[i] = mems[(op.P3 + 1) + i + 1]; //: args[i] = argc[i + 1];
                                    MemStoreType(args[i]);
                                }

                                InVtabMethod = 1;
                                rc = module.Filter(vtabCursor, queryLength, op.P4.Z, argsLength, args);
                                InVtabMethod = 0;
                                ImportVtabErrMsg(this, vtable);
                                if (rc == RC.OK)
                                    res = module.Eof(vtabCursor);

                                if (res != 0)
                                    pc = op.P2 - 1;
                            }
                            cur.NullRow = false;
                            break;
                        }
                    case OP.VColumn:
                        {
                            // Opcode: VColumn P1 P2 P3 * *
                            //
                            // Store the value of the P2-th column of the row of the virtual-table that the P1 cursor is pointing to into register P3.
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur.VtabCursor != null);
                            Debug.Assert(op.P3 > 0 && op.P3 <= Mems.length);
                            Mem dest = mems[op.P3];
                            MemAboutToChange(this, dest);
                            if (cur.NullRow)
                            {
                                MemSetNull(dest);
                                break;
                            }
                            IVTable vtable = cur.VtabCursor.IVTable;
                            ITableModule module = vtable.IModule;
                            Debug.Assert(module.Column != null);
                            FuncContext sContext = new FuncContext();

                            // The output cell may already have a buffer allocated. Move the current contents to sContext.s so in case the user-function 
                            // can use the already allocated buffer instead of allocating a new one.
                            MemMove(sContext.S, dest);
                            E.MemSetTypeFlag(sContext.S, MEM.Null);

                            rc = module.Column(cur.VtabCursor, sContext, op.P2);
                            ImportVtabErrMsg(this, vtable);
                            if (sContext.IsError != 0)
                                rc = sContext.IsError;

                            // Copy the result of the function to the P3 register. We do this regardless of whether or not an error occurred to ensure any
                            // dynamic allocation in sContext.s (a Mem struct) is released.
                            ChangeEncoding(sContext.S, encoding);
                            MemMove(dest, sContext.S);
                            REGISTER_TRACE(op.P3, dest);
                            UPDATE_MAX_BLOBSIZE(dest);

                            if (MemTooBig(dest))
                                goto too_big;
                            break;
                        }
                    case OP.VNext: // jump
                        {
                            // Opcode: VNext P1 P2 * * *
                            //
                            // Advance virtual table P1 to the next row in its result set and jump to instruction P2.  Or, if the virtual table has reached
                            // the end of its result set, then fall through to the next instruction.
                            int res = 0;
                            VdbeCursor cur = Cursors[op.P1];
                            Debug.Assert(cur.VtabCursor != null);
                            if (cur.NullRow)
                                break;
                            IVTable vtable = cur.VtabCursor.IVTable;
                            ITableModule module = vtable.IModule;
                            Debug.Assert(module.Next != null);

                            // Invoke the xNext() method of the module. There is no way for the underlying implementation to return an error if one occurs during
                            // xNext(). Instead, if an error occurs, true is returned (indicating that data is available) and the error code returned when xColumn or
                            // some other method is next invoked on the save virtual table cursor.
                            InVtabMethod = 1;
                            rc = module.Next(cur.VtabCursor);
                            InVtabMethod = 0;
                            ImportVtabErrMsg(this, vtable);
                            if (rc == RC.OK)
                                res = module.Eof(cur.VtabCursor);

                            if (res == 0)
                                pc = op.P2 - 1;// If there is data, jump to P2
                            break;
                        }
                    case OP.VRename:
                        {
                            // Opcode: VRename P1 * * P4 *
                            //
                            // P4 is a pointer to a virtual table object, an sqlite3_vtab structure. This opcode invokes the corresponding xRename method. The value
                            // in register P1 is passed as the zName argument to the xRename method.
                            IVTable vtable = op.P4.VTable.IVTable;
                            Mem name = mems[op.P1];
                            Debug.Assert(vtable.IModule.Rename != null);
                            Debug.Assert(E.MemIsValid(name));
                            REGISTER_TRACE(op.P1, name);
                            Debug.Assert((name.Flags & MEM.Str) != 0);
                            rc = ChangeEncoding(name, TEXTENCODE.UTF8);
                            if (rc == RC.OK)
                            {
                                rc = vtable.IModule.Rename(vtable, name.Z);
                                ImportVtabErrMsg(this, vtable);
                                Expired = false;
                            }
                            break;
                        }
                    case OP.VUpdate:
                        {
                            // Opcode: VUpdate P1 P2 P3 P4 *
                            //
                            // P4 is a pointer to a virtual table object, an sqlite3_vtab structure. This opcode invokes the corresponding xUpdate method. P2 values
                            // are contiguous memory cells starting at P3 to pass to the xUpdate invocation. The value in register (P3+P2-1) corresponds to the 
                            // p2th element of the argv array passed to xUpdate.
                            //
                            // The xUpdate method will do a DELETE or an INSERT or both. The argv[0] element (which corresponds to memory cell P3)
                            // is the rowid of a row to delete.  If argv[0] is NULL then no deletion occurs.  The argv[1] element is the rowid of the new 
                            // row.  This can be NULL to have the virtual table select the new rowid for itself.  The subsequent elements in the array are 
                            // the values of columns in the new row.
                            //
                            // If P2==1 then no insert is performed.  argv[0] is the rowid of a row to delete.
                            //
                            // P1 is a boolean flag. If it is set to true and the xUpdate call is successful, then the value returned by sqlite3_last_insert_rowid() 
                            // is set to the value of the rowid for the row just inserted.
                            Debug.Assert(op.P2 == 1 || (OE)op.P5 == OE.Fail || (OE)op.P5 == OE.Rollback || (OE)op.P5 == OE.Abort || (OE)op.P5 == OE.Ignore || (OE)op.P5 == OE.Replace);
                            IVTable vtable = op.P4.VTable.IVTable;
                            ITableModule module = (ITableModule)vtable.IModule;
                            int argsLength = op.P2;
                            Debug.Assert(op.P4Type == Vdbe.P4T.VTAB);
                            if (C._ALWAYS(module.Update))
                            {
                                byte vtabOnConflict = ctx.VTableOnConflict;
                                Mem[] args = Args;
                                Mem x; //: x = mems[op.P3];
                                for (int i = 0; i < argsLength; i++)
                                {
                                    x = mems[op.P3 + i];
                                    Debug.Assert(E.MemIsValid(x));
                                    MemAboutToChange(this, x);
                                    MemStoreType(x);
                                    args[i] = x;
                                    //: x++;
                                }
                                ctx.VTableOnConflict = op.P5;
                                long rowid = 0;
                                rc = module.Update(vtable, argsLength, args, out rowid);
                                ctx.VTableOnConflict = vtabOnConflict;
                                ImportVtabErrMsg(p, vtable);
                                if (rc == RC.OK && op.P1 != 0)
                                {
                                    Debug.Assert(argsLength > 1 && args[0] != null && (args[0].Flags & MEM.Null) != 0);
                                    ctx.LastRowID = lastRowid = rowid;
                                }
                                if ((RC)(rc & 0xff) == RC.CONSTRAINT && op.P4.VTable.Constraint)
                                {
                                    if ((OE)op.P5 == OE.Ignore)
                                        rc = RC.OK;
                                    else
                                        ErrorAction = ((OE)op.P5 == OE.Replace ? OE.Abort : (OE)op.P5);
                                }
                                else
                                    Changes++;
                            }
                            break;
                        }
#endif
                    #endregion
#if !OMIT_PAGER_PRAGMAS
                    case OP.Pagecount: // out2-prerelease
                        {
                            // Opcode: Pagecount P1 P2 * * *
                            //
                            // Write the current number of pages in database P1 to memory cell P2.
                            out_.u.I = ctx.DBs[op.P1].Bt.LastPage();
                            break;
                        }
                    case OP.MaxPgcnt: // out2-prerelease
                        {
                            // Opcode: MaxPgcnt P1 P2 P3 * *
                            //
                            // Try to set the maximum page count for database P1 to the value in P3. Do not let the maximum page count fall below the current page count and
                            // do not change the maximum page count value if P3==0.
                            //
                            // Store the maximum page count after the change in register P2.
                            Btree bt = ctx.DBs[op.P1].Bt;
                            long newMax = 0;
                            if (op.P3 != 0)
                            {
                                newMax = bt.LastPage();
                                if (newMax < op.P3) newMax = op.P3;
                            }
                            out_.u.I = (long)bt.MaxPageCount((int)newMax);
                            break;
                        }
#endif
#if !OMIT_TRACE
                    case OP.Trace:
                        {
                            // Opcode: Trace * * * P4 *
                            //
                            // If tracing is enabled (by the sqlite3_trace()) interface, then the UTF-8 string contained in P4 is emitted on the trace callback.
                            string trace;
                            string z;
                            if (ctx.Trace != null && !DoingRerun && (trace = (op.P4.Z != null ? op.P4.Z : Sql_)) != null)
                            {
                                z = ExpandSql(trace);
                                ctx.Trace(ctx.TraceArg, z);
                                C._tagfree(ctx, ref z);
                            }
#if DEBUG
                            if ((ctx.Flags & Context.FLAG.SqlTrace) != 0 && (trace = (op.P4.Z != null ? op.P4.Z : Sql_)) != null)
                                _dprintf("SQL-trace: %s\n", trace);
#endif
                            break;
                        }
#endif
                    default: // This is really OP_Noop and OP_Explain
                        {
                            // Opcode: Noop * * * * *
                            //
                            // Do nothing.  This instruction is often useful as a jump destination.
                            //
                            // The magic Explain opcode are only inserted when explain==2 (which is to say when the EXPLAIN QUERY PLAN syntax is used.)
                            // This opcode records information from the optimizer.  It is the the same as a no-op.  This opcodesnever appears in a real VM program.
                            Debug.Assert(op.Opcode == OP.Noop || op.Opcode == OP.Explain);
                            break;
                        }
                }
                // The cases of the switch statement above this line should all be indented by 6 spaces.  But the left-most 6 spaces have been removed to improve the
                // readability.  From this point on down, the normal indentation rules are restored.

#if VDBE_PROFILE
                {
                    ulong elapsed = C._hwtime() - start;
                    op.Cycles += elapsed;
                    op.Cnt++;
#if false
Console.Write("%10llu ", elapsed);
PrintOp(Console.Out, origPc, ops[origPc]);
#endif
                }
#endif

#if !NDEBUG
                // The following code adds nothing to the actual functionality of the program.  It is only here for testing and debugging.
                // On the other hand, it does burn CPU cycles every time through the evaluator loop.  So we can leave it out when NDEBUG is defined.
                Debug.Assert(pc >= -1 && pc < Ops.length);
#if DEBUG
                if (Trace != null)
                {
                    if (rc != 0)
                        fprintf(Trace, "rc=%d\n", rc);
                    if ((op.Opflags & (OPFLG.OUT2_PRERELEASE | OPFLG.OUT2)) != 0)
                        RegisterTrace(Trace, op.P2, mems[op.P2]);
                    if ((op.Opflags & OPFLG.OUT3) != 0)
                        RegisterTrace(Trace, op.P3, mems[op.P3]);
                }
#endif
#endif
            }  // The end of the for(;;) loop the loops through opcodes

        // If we reach this point, it means that execution is finished with an error of some kind.
        vdbe_error_halt:
            Debug.Assert(rc != 0);
            RC_ = rc;
            C.ASSERTCOVERAGE(SysEx._GlobalStatics.Log != null);
            SysEx.LOG(rc, "statement aborts at %d: [%s] %s", pc, Sql_, ErrMsg);
            Halt();
            if (rc == RC.IOERR_NOMEM) ctx.MallocFailed = true;
            rc = RC.ERROR;
            if (resetSchemaOnFault > 0)
                Parse.ResetOneSchema(ctx, resetSchemaOnFault - 1);

        // This is the only way out of this procedure.  We have to release the mutexes on btrees that were acquired at the top.
        vdbe_return:
            ctx.LastRowID = lastRowid;
            Leave();
            return rc;

        // Jump to here if a string or blob larger than CORE_MAX_LENGTH is encountered.
        too_big:
            C._setstring(ref ErrMsg, ctx, "string or blob too big");
            rc = RC.TOOBIG;
            goto vdbe_error_halt;

        // Jump to here if a malloc() fails.
        no_mem:
            ctx.MallocFailed = true;
            C._setstring(ref ErrMsg, ctx, "out of memory");
            rc = RC.NOMEM;
            goto vdbe_error_halt;

        // Jump to here for any other kind of fatal error.  The "rc" variable should hold the error number.
        abort_due_to_error:
            Debug.Assert(ErrMsg != null);
            if (ctx.MallocFailed) rc = RC.NOMEM;
            if (rc != RC.IOERR_NOMEM)
                C._setstring(ref ErrMsg, ctx, "%s", Main.ErrStr(rc));
            goto vdbe_error_halt;

        // Jump to here if the sqlite3_interrupt() API sets the interrupt flag.
        abort_due_to_interrupt:
            Debug.Assert(ctx.u1.IsInterrupted);
            rc = RC.INTERRUPT;
            RC_ = rc;
            C._setstring(ref ErrMsg, ctx, Main.ErrStr(rc));
            goto vdbe_error_halt;
        }
예제 #3
0
파일: Btree.cs 프로젝트: BclEx/GpuStructs
        public static RC MovetoUnpacked(BtCursor cur, UnpackedRecord idxKey, long intKey, int biasRight, out int res)
        {
            Debug.Assert(cursorHoldsMutex(cur));
            Debug.Assert(MutexEx.Held(cur.Btree.Ctx.Mutex));
            Debug.Assert((idxKey == null) == (cur.KeyInfo == null));

            // If the cursor is already positioned at the point we are trying to move to, then just return without doing any work
            if (cur.State == CURSOR.VALID && cur.ValidNKey && cur.Pages[0].IntKey)
            {
                if (cur.Info.Key == intKey)
                {
                    res = 0;
                    return RC.OK;
                }
                if (cur.AtLast != 0 && cur.Info.Key < intKey)
                {
                    res = -1;
                    return RC.OK;
                }
            }

            res = -1;
            var rc = moveToRoot(cur);
            if (rc != RC.OK)
                return rc;
            Debug.Assert(cur.RootID == 0 || cur.Pages[cur.ID] != null);
            Debug.Assert(cur.RootID == 0 || cur.Pages[cur.ID].IsInit);
            Debug.Assert(cur.State == CURSOR.INVALID || cur.Pages[cur.ID].Cells > 0);
            if (cur.State == CURSOR.INVALID)
            {
                res = -1;
                Debug.Assert(cur.RootID == 0 || cur.Pages[cur.ID].Cells == 0);
                return RC.OK;
            }
            Debug.Assert(cur.Pages[0].IntKey || idxKey != null);
            int c;
            for (; ; )
            {
                // pPage->nCell must be greater than zero. If this is the root-page the cursor would have been INVALID above and this for(;;) loop
                // not run. If this is not the root-page, then the moveToChild() routine would have already detected db corruption. Similarly, pPage must
                // be the right kind (index or table) of b-tree page. Otherwise a moveToChild() or moveToRoot() call would have detected corruption.
                MemPage page = cur.Pages[cur.ID];
                Debug.Assert(page.Cells > 0);
                Debug.Assert(page.IntKey == (idxKey == null));
                uint idx;
                uint lwr = 0;
                uint upr = (uint)(page.Cells - 1);
                if (biasRight != 0)
                    cur.Idxs[cur.ID] = (ushort)(idx = upr);
                else
                    cur.Idxs[cur.ID] = (ushort)(idx = (upr + lwr) / 2);
                for (; ; )
                {
                    Debug.Assert(idx == cur.Idxs[cur.ID]);
                    cur.Info.Size = 0;
                    uint cell_ = findCell(page, idx) + page.ChildPtrSize; // Pointer to current cell in pPage
                    if (page.IntKey)
                    {
                        if (page.HasData)
                        {
                            uint dummy = 0;
                            cell_ += ConvertEx.GetVarint32(page.Data, cell_, out dummy);
                        }
                        long cellKeyLength = 0;
                        ConvertEx.GetVarint(page.Data, cell_, out cellKeyLength);
                        if (cellKeyLength == intKey)
                            c = 0;
                        else if (cellKeyLength < intKey)
                            c = -1;
                        else
                            c = +1;
                        cur.ValidNKey = true;
                        cur.Info.Key = cellKeyLength;
                    }
                    else
                    {
                        // The maximum supported page-size is 65536 bytes. This means that the maximum number of record bytes stored on an index B-Tree
                        // page is less than 16384 bytes and may be stored as a 2-byte varint. This information is used to attempt to avoid parsing 
                        // the entire cell by checking for the cases where the record is stored entirely within the b-tree page by inspecting the first 
                        // 2 bytes of the cell.
                        int cellLength = page.Data[cell_ + 0];
                        if (cellLength <= page.Max1bytePayload)
                        {
                            // This branch runs if the record-size field of the cell is a single byte varint and the record fits entirely on the main b-tree page.
                            c = _vdbe.RecordCompare(cellLength, page.Data, cell_ + 1, idxKey);
                        }
                        else if ((page.Data[cell_ + 1] & 0x80) == 0 && (cellLength = ((cellLength & 0x7f) << 7) + page.Data[cell_ + 1]) <= page.MaxLocal)
                        {
                            // The record-size field is a 2 byte varint and the record fits entirely on the main b-tree page.
                            c = _vdbe.RecordCompare(cellLength, page.Data, cell_ + 2, idxKey);
                        }
                        else
                        {
                            // The record flows over onto one or more overflow pages. In this case the whole cell needs to be parsed, a buffer allocated
                            // and accessPayload() used to retrieve the record into the buffer before VdbeRecordCompare() can be called.
                            var cellBody = new byte[page.Data.Length - cell_ + page.ChildPtrSize];
                            Buffer.BlockCopy(page.Data, (int)cell_ - page.ChildPtrSize, cellBody, 0, cellBody.Length);
                            btreeParseCellPtr(page, cellBody, ref cur.Info);
                            cellLength = (int)cur.Info.Key;
                            var cellKey = C._alloc(cellLength);
                            rc = accessPayload(cur, 0, (uint)cellLength, cellKey, 0);
                            if (rc != RC.OK)
                            {
                                cellKey = null;
                                goto moveto_finish;
                            }
                            c = _vdbe.RecordCompare(cellLength, cellKey, 0, idxKey);
                            cellKey = null;
                        }
                    }
                    if (c == 0)
                    {
                        if (page.IntKey && !page.Leaf)
                        {
                            lwr = idx;
                            upr = lwr - 1;
                            break;
                        }
                        else
                        {
                            res = 0;
                            rc = RC.OK;
                            goto moveto_finish;
                        }
                    }
                    if (c < 0)
                        lwr = idx + 1;
                    else
                        upr = idx - 1;
                    if (lwr > upr)
                        break;
                    cur.Idxs[cur.ID] = (ushort)(idx = (lwr + upr) / 2);
                }
                Debug.Assert(lwr == upr + 1 || (page.IntKey && !page.Leaf));
                Debug.Assert(page.IsInit);
                Pid childID;
                if (page.Leaf)
                    childID = 0;
                else if (lwr >= page.Cells)
                    childID = ConvertEx.Get4(page.Data, page.HdrOffset + 8);
                else
                    childID = ConvertEx.Get4(page.Data, findCell(page, lwr));
                if (childID == 0)
                {
                    Debug.Assert(cur.Idxs[cur.ID] < cur.Pages[cur.ID].Cells);
                    res = (int)c;
                    rc = RC.OK;
                    goto moveto_finish;
                }
                cur.Idxs[cur.ID] = (ushort)lwr;
                cur.Info.Size = 0;
                cur.ValidNKey = false;
                rc = moveToChild(cur, childID);
                if (rc != RC.OK) goto moveto_finish;
            }
        moveto_finish:
            return rc;
        }
예제 #4
0
 int Vdbe_RecordCompare(int cells, byte[] cellKey, uint offset_, UnpackedRecord idxKey);
예제 #5
0
 void Vdbe_DeleteUnpackedRecord(UnpackedRecord r);
예제 #6
0
 void Vdbe_RecordUnpack(KeyInfo keyInfo, int keyLength, byte[] key, UnpackedRecord p);
예제 #7
0
 public static int IdxKeyCompare(VdbeCursor c, UnpackedRecord unpacked, ref int r)
 {
     Btree.BtCursor cur = c.Cursor;
     Mem m = null;
     Debug.Assert(Btree.CursorIsValid(cur));
     long cellKeyLength = 0;
     RC rc = Btree.KeySize(cur, ref cellKeyLength);
     Debug.Assert(rc == RC.OK); // pCur is always valid so KeySize cannot fail
     // nCellKey will always be between 0 and 0xffffffff because of the say that btreeParseCellPtr() and sqlite3GetVarint32() are implemented
     if (cellKeyLength <= 0 || cellKeyLength > 0x7fffffff)
     {
         r = 0;
         return SysEx.CORRUPT_BKPT();
     }
     m = C._alloc(m); //: _memset(&m, 0, sizeof(m));
     rc = MemFromBtree(cur, 0, (int)cellKeyLength, true, m);
     if (rc != 0)
         return rc;
     Debug.Assert((unpacked.Flags & UNPACKED_IGNORE_ROWID) != 0);
     r = RecordCompare(m.N, m.Z_, unpacked);
     MemRelease(m);
     return RC.OK;
 }
예제 #8
0
        // ALTERNATE FORM for C#
        //public static int RecordCompare(int key1Length, byte[] key1, UnpackedRecord key2) { return sqlite3VdbeRecordCompare(key1Length, key1, 0, key2); }
        public static int RecordCompare(int key1Length, byte[] key1, uint offset, UnpackedRecord key2)
        {
            int i = 0;
            int rc = 0;
            byte[] key1s = new byte[key1.Length - offset];

            KeyInfo keyInfo = key2.pKeyInfo;
            _mem1.Encode = keyInfo.Encode;
            _mem1.Ctx = (Context)keyInfo.Ctx;
            // _mem1.flags = 0; // Will be initialized by sqlite3VdbeSerialGet()
            // ASSERTONLY(mem1.Malloc = 0;) // Only needed by Debug.Assert() statements

            // Compilers may complain that mem1.u.i is potentially uninitialized. We could initialize it, as shown here, to silence those complaints.
            // But in fact, mem1.u.i will never actually be used uninitialized, and doing the unnecessary initialization has a measurable negative performance
            // impact, since this routine is a very high runner.  And so, we choose to ignore the compiler warnings and leave this variable uninitialized.
            //  _mem1.u.i = 0;  // not needed, here to silence compiler warning
            uint szHdr1; // Number of bytes in header
            uint idx1 = (uint)(ConvertEx.GetVarint32(key1, offset, out szHdr1)); // Offset into aKey[] of next header element
            int d1 = (int)szHdr1; // Offset into aKey[] of next data element
            int fields = keyInfo.Fields;
            Debug.Assert(keyInfo.SortOrders != null);
            while (idx1 < szHdr1 && i < key2.Fields)
            {
                uint serialType1;

                // Read the serial types for the next element in each key.
                idx1 += (uint)(ConvertEx.GetVarint32(key1s, (uint)(offset + idx1), out serialType1));
                if (d1 <= 0 || d1 >= key1Length && SerialTypeLen(serialType1) > 0) break;

                // Extract the values to be compared.
                d1 += (int)SerialGet(key1s, offset + d1, serialType1, _mem1);

                // Do the comparison
                rc = MemCompare(_mem1, key2.Mems[i], (i < fields ? keyInfo.Colls[i] : null));
                if (rc != 0)
                {
                    //: Debug.Assert(_mem1.Malloc == null); // See comment below

                    // Invert the result if we are using DESC sort order.
                    if (i < fields && keyInfo.SortOrders != null && keyInfo.SortOrders[i] != 0)
                        rc = -rc;

                    // If the PREFIX_SEARCH flag is set and all fields except the final rowid field were equal, then clear the PREFIX_SEARCH flag and set 
                    // pPKey2->rowid to the value of the rowid field in (pKey1, nKey1). This is used by the OP_IsUnique opcode.
                    if ((key2.Flags & UNPACKED_PREFIX_SEARCH) != 0 && i == (key2.Fields - 1))
                    {
                        Debug.Assert(idx1 == szHdr1 && rc != 0);
                        Debug.Assert((_mem1.flags & MEM_Int) != 0);
                        key2.Flags &= ~UNPACKED_PREFIX_SEARCH;
                        key2.Rowid = _mem1.u.I;
                    }
                    return rc;
                }
                i++;
            }

            // No memory allocation is ever used on mem1.  Prove this using the following assert().  If the assert() fails, it indicates a
            // memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
            //Debug.Assert(mem1.Malloc == null);

            // rc==0 here means that one of the keys ran out of fields and all the fields up to that point were equal. If the UNPACKED_INCRKEY
            // flag is set, then break the tie by treating key2 as larger. If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
            // are considered to be equal.  Otherwise, the longer key is the larger.  As it happens, the pPKey2 will always be the longer
            // if there is a difference.
            Debug.Assert(rc == 0);
            if ((key2.Flags & UNPACKED_INCRKEY) != 0) rc = -1;
            else if ((key2.flags & UNPACKED_PREFIX_MATCH) != 0) { } // Leave rc==0 
            else if (idx1 < szHdr1) rc = 1;
            return rc;
        }
예제 #9
0
 public static void RecordUnpack(KeyInfo keyInfo, int keyLength, byte[] key, UnpackedRecord p)
 {
     byte[] keys = key;
     Mem mem;
     p.Flags = 0;
     //: Debug.Assert(C._HASALIGNMENT8(mem));
     int szHdr;
     uint idx = (uint)ConvertEx.GetVarint32(keys, 0, out szHdr);
     int d = szHdr;
     ushort u = 0; // Unsigned loop counter
     while (idx < szHdr && u < p.Fields && d <= keyLength)
     {
         p.Mems[u] = mem = C._alloc(p.Mems[u]);
         uint serialType;
         idx += (uint)ConvertEx.GetVarint32(keys, idx, out serialType);
         mem.Encode = keyInfo.Encode;
         mem.Ctx = (Context)keyInfo.Ctx;
         //mem->Flags = 0; // sqlite3VdbeSerialGet() will set this for us
         //: mem.Malloc = null;
         d += (int)SerialGet(keys, d, serialType, mem);
         u++;
     }
     Debug.Assert(u <= keyInfo.Fields + 1);
     p.Fields = (ushort)u;
 }
예제 #10
0
 public static UnpackedRecord AllocUnpackedRecord(KeyInfo keyInfo)
 {
     var p = new UnpackedRecord();
     p.Mems = new Mem[p.Fields + 1];
     p.KeyInfo = keyInfo;
     p.Fields = (ushort)(keyInfo.Fields + 1);
     return p;
 }