public static void GenerateRowDelete(Parse parse, Table table, int curId, int rowid, int count, Trigger trigger, OE onconf)
{
// Vdbe is guaranteed to have been allocated by this stage.
Vdbe v = parse.V;
Debug.Assert(v != null);
// Seek cursor iCur to the row to delete. If this row no longer exists (this can happen if a trigger program has already deleted it), do
// not attempt to delete it or fire any DELETE triggers.
int label = v.MakeLabel(); // Label resolved to end of generated code
v.AddOp3(OP.NotExists, curId, label, rowid);
// If there are any triggers to fire, allocate a range of registers to use for the old.* references in the triggers.
if (FKey.FkRequired(parse, table, null, 0) != 0 || trigger != null)
{
// TODO: Could use temporary registers here. Also could attempt to avoid copying the contents of the rowid register.
uint mask = sqlite3TriggerColmask(parse, trigger, null, 0, TRIGGER.BEFORE | TRIGGER.AFTER, table, onconf); // Mask of OLD.* columns in use
mask |= sqlite3FkOldmask(parse, table);
int oldId = parse.Mems + 1; // First register in OLD.* array
parse.Mems += (1 + table.Cols.length);
// Populate the OLD.* pseudo-table register array. These values will be used by any BEFORE and AFTER triggers that exist.
v.AddOp2(OP.Copy, rowid, oldId);
for (int col = 0; col < table.Cols.length; col++) // Iterator used while populating OLD.*
if (mask == 0xffffffff || (mask & (1 << col)) != 0)
Expr.CodeGetColumnOfTable(v, table, curId, col, oldId + col + 1);
// Invoke BEFORE DELETE trigger programs.
sqlite3CodeRowTrigger(parse, trigger, TK.DELETE, null, TRIGGER.BEFORE, table, oldId, onconf, label);
// Seek the cursor to the row to be deleted again. It may be that the BEFORE triggers coded above have already removed the row
// being deleted. Do not attempt to delete the row a second time, and do not fire AFTER triggers.
v.AddOp3(OP.NotExists, curId, label, rowid);
// Do FK processing. This call checks that any FK constraints that refer to this table (i.e. constraints attached to other tables) are not violated by deleting this row.
FKey.FkCheck(parse, table, oldId, 0);
}
// Delete the index and table entries. Skip this step if table is really a view (in which case the only effect of the DELETE statement is to fire the INSTEAD OF triggers).
if (table.Select == null)
{
GenerateRowIndexDelete(parse, table, curId, null);
v.AddOp2(OP.Delete, curId, (count != 0 ? (int)OPFLAG.NCHANGE : 0));
if (count != 0)
v.ChangeP4(-1, table.Name, Vdbe.P4T.TRANSIENT);
}
// Do any ON CASCADE, SET NULL or SET DEFAULT operations required to handle rows (possibly in other tables) that refer via a foreign key to the row just deleted.
FKey.FkActions(parse, table, null, oldId);
// Invoke AFTER DELETE trigger programs.
sqlite3CodeRowTrigger(parse, trigger, TK.DELETE, null, TRIGGER.AFTER, table, oldId, onconf, label);
// Jump here if the row had already been deleted before any BEFORE trigger programs were invoked. Or if a trigger program throws a RAISE(IGNORE) exception.
v.ResolveLabel(label);
}
public static void DeleteFrom(Parse parse, SrcList tabList, Expr where_)
{
AuthContext sContext = new AuthContext(); // Authorization context
Context ctx = parse.Ctx; // Main database structure
if (parse.Errs != 0 || ctx.MallocFailed)
goto delete_from_cleanup;
Debug.Assert(tabList.Srcs == 1);
// Locate the table which we want to delete. This table has to be put in an SrcList structure because some of the subroutines we
// will be calling are designed to work with multiple tables and expect an SrcList* parameter instead of just a Table* parameter.
Table table = SrcList.Lookup(parse, tabList); // The table from which records will be deleted
if (table == null) goto delete_from_cleanup;
// Figure out if we have any triggers and if the table being deleted from is a view
#if !OMIT_TRIGGER
int dummy;
Trigger trigger = Triggers.Exist(parse, table, TK.DELETE, null, out dummy); // List of table triggers, if required
#if OMIT_VIEW
const bool isView = false;
#else
bool isView = (table.Select != null); // True if attempting to delete from a view
#endif
#else
const Trigger trigger = null;
bool isView = false;
#endif
// If pTab is really a view, make sure it has been initialized.
if (sqlite3ViewGetColumnNames(parse, table) != null || IsReadOnly(parse, table, (trigger != null)))
goto delete_from_cleanup;
int db = sqlite3SchemaToIndex(ctx, table.Schema); // Database number
Debug.Assert(db < ctx.DBs.length);
string dbName = ctx.DBs[db].Name; // Name of database holding pTab
ARC rcauth = Auth.Check(parse, AUTH.DELETE, table.Name, 0, dbName); // Value returned by authorization callback
Debug.Assert(rcauth == ARC.OK || rcauth == ARC.DENY || rcauth == ARC.IGNORE);
if (rcauth == ARC.DENY)
goto delete_from_cleanup;
Debug.Assert(!isView || trigger != null);
// Assign cursor number to the table and all its indices.
Debug.Assert(tabList.Srcs == 1);
int curId = tabList.Ids[0].Cursor = parse.Tabs++; // VDBE VdbeCursor number for pTab
Index idx; // For looping over indices of the table
for (idx = table.Index; idx != null; idx = idx.Next)
parse.Tabs++;
// Start the view context
if (isView)
Auth.ContextPush(parse, sContext, table.Name);
// Begin generating code.
Vdbe v = parse.GetVdbe(); // The virtual database engine
if (v == null)
goto delete_from_cleanup;
if (parse.Nested == 0) v.CountChanges();
parse.BeginWriteOperation(1, db);
// If we are trying to delete from a view, realize that view into a ephemeral table.
#if !OMIT_VIEW && !OMIT_TRIGGER
if (isView)
MaterializeView(parse, table, where_, curId);
#endif
// Resolve the column names in the WHERE clause.
NameContext sNC = new NameContext(); // Name context to resolve expressions in
sNC.Parse = parse;
sNC.SrcList = tabList;
if (sqlite3ResolveExprNames(sNC, ref where_) != 0)
goto delete_from_cleanup;
// Initialize the counter of the number of rows deleted, if we are counting rows.
int memCnt = -1; // Memory cell used for change counting
if ((ctx.Flags & Context.FLAG.CountRows) != 0)
{
memCnt = ++parse.Mems;
v.AddOp2(OP.Integer, 0, memCnt);
}
#if !OMIT_TRUNCATE_OPTIMIZATION
// Special case: A DELETE without a WHERE clause deletes everything. It is easier just to erase the whole table. Prior to version 3.6.5,
// this optimization caused the row change count (the value returned by API function sqlite3_count_changes) to be set incorrectly.
if (rcauth == ARC.OK && where_ == null && trigger == null && !IsVirtual(table) && !FKey.FkRequired(parse, table, null, 0))
{
Debug.Assert(!isView);
v.AddOp4(OP.Clear, table.Id, db, memCnt, table.Name, Vdbe.P4T.STATIC);
for (idx = table.Index; idx != null; idx = idx.Next)
{
Debug.Assert(idx.Schema == table.Schema);
v.AddOp2(OP.Clear, idx.Id, db);
}
}
else
#endif
// The usual case: There is a WHERE clause so we have to scan through the table and pick which records to delete.
{
int rowSet = ++parse.Mems; // Register for rowset of rows to delete
int rowid = ++parse.Mems; // Used for storing rowid values.
// Collect rowids of every row to be deleted.
v.AddOp2(OP.Null, 0, rowSet);
ExprList dummy = null;
WhereInfo winfo = Where.Begin(parse, tabList, where_, ref dummy, WHERE_DUPLICATES_OK, 0); // Information about the WHERE clause
if (winfo == null) goto delete_from_cleanup;
int regRowid = Expr.CodeGetColumn(parse, table, -1, curId, rowid); // Actual register containing rowids
v.AddOp2(OP.RowSetAdd, rowSet, regRowid);
if ((ctx.Flags & Context.FLAG.CountRows) != 0)
v.AddOp2(OP.AddImm, memCnt, 1);
Where.End(winfo);
// Delete every item whose key was written to the list during the database scan. We have to delete items after the scan is complete
// because deleting an item can change the scan order.
int end = v.MakeLabel();
// Unless this is a view, open cursors for the table we are deleting from and all its indices. If this is a view, then the
// only effect this statement has is to fire the INSTEAD OF triggers.
if (!isView)
sqlite3OpenTableAndIndices(parse, table, curId, OP.OpenWrite);
int addr = v.AddOp3(OP.RowSetRead, rowSet, end, rowid);
// Delete the row
#if !OMIT_VIRTUALTABLE
if (IsVirtual(table))
{
VTable vtable = VTable.GetVTable(ctx, table);
VTable.MakeWritable(parse, table);
v.AddOp4(OP.VUpdate, 0, 1, rowid, vtable, Vdbe.P4T.VTAB);
v.ChangeP5(OE.Abort);
sqlite3MayAbort(parse);
}
else
#endif
{
int count = (parse.Nested == 0; // True to count changes
GenerateRowDelete(parse, table, curId, rowid, count, trigger, OE.Default);
}
// End of the delete loop
v.AddOp2(OP.Goto, 0, addr);
v.ResolveLabel(end);
// Close the cursors open on the table and its indexes.
if (!isView && !IsVirtual(table))
{
for (int i = 1, idx = table.Index; idx != null; i++, idx = idx.Next)
v.AddOp2(OP.Close, curId + i, idx.Id);
v.AddOp1(OP.Close, curId);
}
}
// Update the sqlite_sequence table by storing the content of the maximum rowid counter values recorded while inserting into
// autoincrement tables.
if (parse.Nested == 0 && parse.TriggerTab == null)
sqlite3AutoincrementEnd(parse);
// Return the number of rows that were deleted. If this routine is generating code because of a call to sqlite3NestedParse(), do not
// invoke the callback function.
if ((ctx.Flags & Context.FLAG.CountRows) != 0 && parse.Nested == 0 && parse.TriggerTab == null)
{
v.AddOp2(OP.ResultRow, memCnt, 1);
v.SetNumCols(1);
v.SetColName(0, COLNAME_NAME, "rows deleted", SQLITE_STATIC);
}
delete_from_cleanup:
Auth.ContextPop(sContext);
SrcList.Delete(ctx, ref tabList);
Expr.Delete(ctx, ref where_);
return;
}
static void AnalyzeOneTable(Parse parse, Table table, Index onlyIdx, int statCurId, int memId)
{
Context ctx = parse.Ctx; // Database handle
int i; // Loop counter
int regTabname = memId++; // Register containing table name
int regIdxname = memId++; // Register containing index name
int regSampleno = memId++; // Register containing next sample number
int regCol = memId++; // Content of a column analyzed table
int regRec = memId++; // Register holding completed record
int regTemp = memId++; // Temporary use register
int regRowid = memId++; // Rowid for the inserted record
Vdbe v = parse.GetVdbe(); // The virtual machine being built up
if (v == null || C._NEVER(table == null))
{
return;
}
// Do not gather statistics on views or virtual tables or system tables
if (table.Id == 0 || table.Name.StartsWith("sqlite_", StringComparison.OrdinalIgnoreCase))
{
return;
}
Debug.Assert(Btree.HoldsAllMutexes(ctx));
int db = sqlite3SchemaToIndex(ctx, table.Schema); // Index of database containing pTab
Debug.Assert(db >= 0);
Debug.Assert(Btree.SchemaMutexHeld(ctx, db, null));
#if !OMIT_AUTHORIZATION
if (Auth.Check(parse, AUTH.ANALYZE, table.Name, 0, ctx.DBs[db].Name))
{
return;
}
#endif
// Establish a read-lock on the table at the shared-cache level.
sqlite3TableLock(parse, db, table.Id, 0, table.Name);
int zeroRows = -1; // Jump from here if number of rows is zero
int idxCurId = parse.Tabs++; // Cursor open on index being analyzed
v.AddOp4(OP.String8, 0, regTabname, 0, table.Name, 0);
for (Index idx = table.Index; idx != null; idx = idx.Next) // An index to being analyzed
{
if (onlyIdx != null && onlyIdx != idx)
{
continue;
}
v.NoopComment("Begin analysis of %s", idx.Name);
int cols = idx.Columns.length;
int[] chngAddrs = C._tagalloc <int>(ctx, cols); // Array of jump instruction addresses
if (chngAddrs == null)
{
continue;
}
KeyInfo key = sqlite3IndexKeyinfo(parse, idx);
if (memId + 1 + (cols * 2) > parse.Mems)
{
parse.Mems = memId + 1 + (cols * 2);
}
// Open a cursor to the index to be analyzed.
Debug.Assert(db == sqlite3SchemaToIndex(ctx, idx.Schema));
v.AddOp4(OP.OpenRead, idxCurId, idx.Id, db, key, Vdbe.P4T.KEYINFO_HANDOFF);
v.VdbeComment("%s", idx.Name);
// Populate the registers containing the index names.
v.AddOp4(OP.String8, 0, regIdxname, 0, idx.Name, 0);
#if ENABLE_STAT3
bool once = false; // One-time initialization
if (once)
{
once = false;
sqlite3OpenTable(parse, tabCurId, db, table, OP.OpenRead);
}
v.AddOp2(OP.Count, idxCurId, regCount);
v.AddOp2(OP.Integer, STAT3_SAMPLES, regTemp1);
v.AddOp2(OP.Integer, 0, regNumEq);
v.AddOp2(OP.Integer, 0, regNumLt);
v.AddOp2(OP.Integer, -1, regNumDLt);
v.AddOp3(OP.Null, 0, regSample, regAccum);
v.AddOp4(OP.Function, 1, regCount, regAccum, (object)_stat3InitFuncdef, Vdbe.P4T.FUNCDEF);
v.ChangeP5(2);
#endif
// The block of memory cells initialized here is used as follows.
//
// iMem:
// The total number of rows in the table.
//
// iMem+1 .. iMem+nCol:
// Number of distinct entries in index considering the left-most N columns only, where N is between 1 and nCol,
// inclusive.
//
// iMem+nCol+1 .. Mem+2*nCol:
// Previous value of indexed columns, from left to right.
//
// Cells iMem through iMem+nCol are initialized to 0. The others are initialized to contain an SQL NULL.
for (i = 0; i <= cols; i++)
{
v.AddOp2(OP.Integer, 0, memId + i);
}
for (i = 0; i < cols; i++)
{
v.AddOp2(OP.Null, 0, memId + cols + i + 1);
}
// Start the analysis loop. This loop runs through all the entries in the index b-tree.
int endOfLoop = v.MakeLabel(); // The end of the loop
v.AddOp2(OP.Rewind, idxCurId, endOfLoop);
int topOfLoop = v.CurrentAddr(); // The top of the loop
v.AddOp2(OP.AddImm, memId, 1);
int addrIfNot = 0; // address of OP_IfNot
for (i = 0; i < cols; i++)
{
v.AddOp3(OP.Column, idxCurId, i, regCol);
if (i == 0) // Always record the very first row
{
addrIfNot = v.AddOp1(OP.IfNot, memId + 1);
}
Debug.Assert(idx.CollNames != null && idx.CollNames[i] != null);
CollSeq coll = sqlite3LocateCollSeq(parse, idx.CollNames[i]);
chngAddrs[i] = v.AddOp4(OP.Ne, regCol, 0, memId + cols + i + 1, coll, Vdbe.P4T.COLLSEQ);
v.ChangeP5(SQLITE_NULLEQ);
v.VdbeComment("jump if column %d changed", i);
#if ENABLE_STAT3
if (i == 0)
{
v.AddOp2(OP.AddImm, regNumEq, 1);
v.VdbeComment("incr repeat count");
}
#endif
}
v.AddOp2(OP.Goto, 0, endOfLoop);
for (i = 0; i < cols; i++)
{
v.JumpHere(chngAddrs[i]); // Set jump dest for the OP_Ne
if (i == 0)
{
v.JumpHere(addrIfNot); // Jump dest for OP_IfNot
#if ENABLE_STAT3
v.AddOp4(OP.Function, 1, regNumEq, regTemp2, (object)Stat3PushFuncdef, Vdbe.P4T.FUNCDEF);
v.ChangeP5(5);
v.AddOp3(OP.Column, idxCurId, idx.Columns.length, regRowid);
v.AddOp3(OP.Add, regNumEq, regNumLt, regNumLt);
v.AddOp2(OP.AddImm, regNumDLt, 1);
v.AddOp2(OP.Integer, 1, regNumEq);
#endif
}
v.AddOp2(OP.AddImm, memId + i + 1, 1);
v.AddOp3(OP.Column, idxCurId, i, memId + cols + i + 1);
}
C._tagfree(ctx, chngAddrs);
// Always jump here after updating the iMem+1...iMem+1+nCol counters
v.ResolveLabel(endOfLoop);
v.AddOp2(OP.Next, idxCurId, topOfLoop);
v.AddOp1(OP.Close, idxCurId);
#if ENABLE_STAT3
v.AddOp4(OP.Function, 1, regNumEq, regTemp2, (object)Stat3PushFuncdef, Vdbe.P4T.FUNCDEF);
v.ChangeP5(5);
v.AddOp2(OP.Integer, -1, regLoop);
int shortJump = v.AddOp2(OP_AddImm, regLoop, 1); // Instruction address
v.AddOp4(OP.Function, 1, regAccum, regTemp1, (object)Stat3GetFuncdef, Vdbe.P4T.FUNCDEF);
v.ChangeP5(2);
v.AddOp1(OP.IsNull, regTemp1);
v.AddOp3(OP.NotExists, tabCurId, shortJump, regTemp1);
v.AddOp3(OP.Column, tabCurId, idx->Columns[0], regSample);
sqlite3ColumnDefault(v, table, idx->Columns[0], regSample);
v.AddOp4(OP.Function, 1, regAccum, regNumEq, (object)Stat3GetFuncdef, Vdbe.P4T.FUNCDEF);
v.ChangeP5(3);
v.AddOp4(OP.Function, 1, regAccum, regNumLt, (object)Stat3GetFuncdef, Vdbe.P4T.FUNCDEF);
v.ChangeP5(4);
v.AddOp4(OP.Function, 1, regAccum, regNumDLt, (object)Stat3GetFuncdef, Vdbe.P4T.FUNCDEF);
v.ChangeP5(5);
v.AddOp4(OP.MakeRecord, regTabname, 6, regRec, "bbbbbb", 0);
v.AddOp2(OP.NewRowid, statCurId + 1, regNewRowid);
v.AddOp3(OP.Insert, statCurId + 1, regRec, regNewRowid);
v.AddOp2(OP.Goto, 0, shortJump);
v.JumpHere(shortJump + 2);
#endif
// Store the results in sqlite_stat1.
//
// The result is a single row of the sqlite_stat1 table. The first two columns are the names of the table and index. The third column
// is a string composed of a list of integer statistics about the index. The first integer in the list is the total number of entries
// in the index. There is one additional integer in the list for each column of the table. This additional integer is a guess of how many
// rows of the table the index will select. If D is the count of distinct values and K is the total number of rows, then the integer is computed
// as:
// I = (K+D-1)/D
// If K==0 then no entry is made into the sqlite_stat1 table.
// If K>0 then it is always the case the D>0 so division by zero is never possible.
v.AddOp2(OP_SCopy, memId, regStat1);
if (zeroRows < 0)
{
zeroRows = v.AddOp1(OP.IfNot, memId);
}
for (i = 0; i < cols; i++)
{
v.AddOp4(OP.String8, 0, regTemp, 0, " ", 0);
v.AddOp3(OP.Concat, regTemp, regStat1, regStat1);
v.AddOp3(OP.Add, memId, memId + i + 1, regTemp);
v.AddOp2(OP.AddImm, regTemp, -1);
v.AddOp3(OP.Divide, memId + i + 1, regTemp, regTemp);
v.AddOp1(OP.ToInt, regTemp);
v.AddOp3(OP.Concat, regTemp, regStat1, regStat1);
}
v.AddOp4(OP.MakeRecord, regTabname, 3, regRec, "aaa", 0);
v.AddOp2(OP.NewRowid, statCurId, regNewRowid);
v.AddOp3(OP.Insert, statCurId, regRec, regNewRowid);
v.ChangeP5(OPFLAG_APPEND);
}
// If the table has no indices, create a single sqlite_stat1 entry containing NULL as the index name and the row count as the content.
if (table.Index == null)
{
v.AddOp3(OP.OpenRead, idxCurId, table->Id, db);
v.VdbeComment("%s", table->Name);
v.AddOp2(OP.Count, idxCurId, regStat1);
v.AddOp1(OP.Close, idxCurId);
zeroRows = v.AddOp1(OP.IfNot, regStat1);
}
else
{
v.JumpHere(zeroRows);
zeroRows = v.AddOp0(OP_Goto);
}
v.AddOp2(OP.Null, 0, regIdxname);
v.AddOp4(OP.MakeRecord, regTabname, 3, regRec, "aaa", 0);
v.AddOp2(OP.NewRowid, statCurId, regNewRowid);
v.AddOp3(OP.Insert, statCurId, regRec, regNewRowid);
v.ChangeP5(OPFLAG_APPEND);
if (parse.Mems < regRec)
{
parse.Mems = regRec;
}
v.JumpHere(zeroRows);
}