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Optimisations for expressions of the form "<value> IN (SELECT <column> FROM <table>)". (CVS 4579)

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FossilOrigin-Name: 56d0e32677744df8570b519fae1c04da4ea4984d
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danielk1977
2007-11-29 17:05:18 +00:00
parent ade8648301
commit 9a96b66810
9 changed files with 469 additions and 34 deletions
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158
src/expr.c
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@@ -12,7 +12,7 @@
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.316 2007/11/12 09:50:26 danielk1977 Exp $
** $Id: expr.c,v 1.317 2007/11/29 17:05:18 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1522,6 +1522,143 @@ struct QueryCoder {
NameContext *pNC; /* Namespace of first enclosing query */
};
#ifdef SQLITE_TEST
int sqlite3_enable_in_opt = 1;
#else
#define sqlite3_enable_in_opt 1
#endif
/*
** This function is used by the implementation of the IN (...) operator.
** It's job is to find or create a b-tree structure that may be used
** either to test for membership of the (...) set or to iterate through
** it's members, skipping duplicates.
**
** The cursor opened on the structure (database table, database index
** or ephermal table) is stored in pX->iTable before this function returns.
** The returned value indicates the structure type, as follows:
**
** IN_INDEX_ROWID - The cursor was opened on a database table.
** IN_INDEX_INDEX - The cursor was opened on a database indec.
** IN_INDEX_EPH - The cursor was opened on a specially created and
** populated epheremal table.
**
** An existing structure may only be used if the SELECT is of the simple
** form:
**
** SELECT <column> FROM <table>
**
** If the mustBeUnique parameter is false, the structure will be used
** for fast set membership tests. In this case an epheremal table must
** be used unless <column> is an INTEGER PRIMARY KEY or an index can
** be found with <column> as it's left-most column.
**
** If mustBeUnique is true, then the structure will be used to iterate
** through the set members, skipping any duplicates. In this case an
** epheremal table must be used unless the selected <column> is guaranteed
** to be unique - either because it is an INTEGER PRIMARY KEY or it
** is unique by virtue of a constraint or implicit index.
*/
int sqlite3FindInIndex(Parse *pParse, Expr *pX, int mustBeUnique){
Select *p;
int eType = 0;
int iTab = pParse->nTab++;
/* The follwing if(...) expression is true if the SELECT is of the
** simple form:
**
** SELECT <column> FROM <table>
**
** If this is the case, it may be possible to use an existing table
** or index instead of generating an epheremal table.
*/
if( sqlite3_enable_in_opt
&& (p=pX->pSelect) && !p->pPrior
&& !p->isDistinct && !p->isAgg && !p->pGroupBy
&& p->pSrc && p->pSrc->nSrc==1 && !p->pSrc->a[0].pSelect
&& !p->pSrc->a[0].pTab->pSelect
&& p->pEList->nExpr==1 && p->pEList->a[0].pExpr->op==TK_COLUMN
&& !p->pLimit && !p->pOffset && !p->pWhere
){
sqlite3 *db = pParse->db;
Index *pIdx;
Expr *pExpr = p->pEList->a[0].pExpr;
int iCol = pExpr->iColumn;
Vdbe *v = sqlite3GetVdbe(pParse);
/* This function is only called from two places. In both cases the vdbe
** has already been allocated. So assume sqlite3GetVdbe() is always
** successful here.
*/
assert(v);
if( iCol<0 ){
int iMem = pParse->nMem++;
int iAddr;
Table *pTab = p->pSrc->a[0].pTab;
int iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
sqlite3VdbeUsesBtree(v, iDb);
sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
iAddr = sqlite3VdbeAddOp(v, OP_If, 0, iMem);
sqlite3VdbeAddOp(v, OP_MemInt, 1, iMem);
sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
eType = IN_INDEX_ROWID;
sqlite3VdbeJumpHere(v, iAddr);
}else{
/* The collation sequence used by the comparison. If an index is to
** be used in place of a temp-table, it must be ordered according
** to this collation sequence.
*/
CollSeq *pReq = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pExpr);
/* Check that the affinity that will be used to perform the
** comparison is the same as the affinity of the column. If
** it is not, it is not possible to use any index.
*/
Table *pTab = p->pSrc->a[0].pTab;
char aff = comparisonAffinity(pX);
int affinity_ok = (pTab->aCol[iCol].affinity==aff||aff==SQLITE_AFF_NONE);
for(pIdx=pTab->pIndex; pIdx && eType==0 && affinity_ok; pIdx=pIdx->pNext){
if( (pIdx->aiColumn[0]==iCol)
&& (pReq==sqlite3FindCollSeq(db, ENC(db), pIdx->azColl[0], -1, 0))
&& (!mustBeUnique || (pIdx->nColumn==1 && pIdx->onError!=OE_None))
){
int iDb;
int iMem = pParse->nMem++;
int iAddr;
char *pKey;
pKey = (char *)sqlite3IndexKeyinfo(pParse, pIdx);
iDb = sqlite3SchemaToIndex(db, pIdx->pSchema);
sqlite3VdbeUsesBtree(v, iDb);
sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
iAddr = sqlite3VdbeAddOp(v, OP_If, 0, iMem);
sqlite3VdbeAddOp(v, OP_MemInt, 1, iMem);
sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
VdbeComment((v, "# %s", pIdx->zName));
sqlite3VdbeOp3(v,OP_OpenRead,iTab,pIdx->tnum,pKey,P3_KEYINFO_HANDOFF);
eType = IN_INDEX_INDEX;
sqlite3VdbeAddOp(v, OP_SetNumColumns, iTab, pIdx->nColumn);
sqlite3VdbeJumpHere(v, iAddr);
}
}
}
}
if( eType==0 ){
sqlite3CodeSubselect(pParse, pX);
eType = IN_INDEX_EPH;
}else{
pX->iTable = iTab;
}
return eType;
}
/*
** Generate code for scalar subqueries used as an expression
@@ -2036,7 +2173,10 @@ void sqlite3ExprCode(Parse *pParse, Expr *pExpr){
int addr;
char affinity;
int ckOffset = pParse->ckOffset;
sqlite3CodeSubselect(pParse, pExpr);
int eType;
int iLabel = sqlite3VdbeMakeLabel(v);
eType = sqlite3FindInIndex(pParse, pExpr, 0);
/* Figure out the affinity to use to create a key from the results
** of the expression. affinityStr stores a static string suitable for
@@ -2055,10 +2195,18 @@ void sqlite3ExprCode(Parse *pParse, Expr *pExpr){
sqlite3VdbeAddOp(v, OP_NotNull, -1, addr+4); /* addr + 0 */
sqlite3VdbeAddOp(v, OP_Pop, 2, 0);
sqlite3VdbeAddOp(v, OP_Null, 0, 0);
sqlite3VdbeAddOp(v, OP_Goto, 0, addr+7);
sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &affinity, 1); /* addr + 4 */
sqlite3VdbeAddOp(v, OP_Found, pExpr->iTable, addr+7);
sqlite3VdbeAddOp(v, OP_Goto, 0, iLabel);
if( eType==IN_INDEX_ROWID ){
int iAddr = sqlite3VdbeCurrentAddr(v)+3;
sqlite3VdbeAddOp(v, OP_MustBeInt, 1, iAddr);
sqlite3VdbeAddOp(v, OP_NotExists, pExpr->iTable, iAddr);
sqlite3VdbeAddOp(v, OP_Goto, pExpr->iTable, iLabel);
}else{
sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &affinity, 1); /* addr + 4 */
sqlite3VdbeAddOp(v, OP_Found, pExpr->iTable, iLabel);
}
sqlite3VdbeAddOp(v, OP_AddImm, -1, 0); /* addr + 6 */
sqlite3VdbeResolveLabel(v, iLabel);
break;
}