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);
}
