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Candidate fix for ticket #3082. Test cases needed. (CVS 5047)

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FossilOrigin-Name: f6313311ddfb1ee2d6660b9be99afe721a8a9aff
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drh
2008-04-25 00:08:38 +00:00
parent ce3d5cf0c7
commit b287f4b646
3 changed files with 49 additions and 16 deletions
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51
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 1.368 2008/04/24 12:36:35 danielk1977 Exp $
** $Id: expr.c,v 1.369 2008/04/25 00:08:38 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1576,6 +1576,45 @@ struct QueryCoder {
#define sqlite3_enable_in_opt 1
#endif
/*
** Return true if the IN operator optimization is enabled and
** the SELECT statement p exists and 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.
*/
#ifndef SQLITE_OMIT_SUBQUERY
static int isCandidateForInOpt(Select *p){
SrcList *pSrc;
ExprList *pEList;
Table *pTab;
if( !sqlite3_enable_in_opt ) return 0; /* IN optimization must be enabled */
if( p==0 ) return 0; /* right-hand side of IN is SELECT */
if( p->pPrior ) return 0; /* Not a compound SELECT */
if( p->isDistinct ) return 0; /* No DISTINCT keyword */
if( p->isAgg ) return 0; /* Contains no aggregate functions */
if( p->pGroupBy ) return 0; /* Has no GROUP BY clause */
if( p->pLimit ) return 0; /* Has no LIMIT clause */
if( p->pOffset ) return 0;
if( p->pWhere ) return 0; /* Has no WHERE clause */
pSrc = p->pSrc;
if( pSrc==0 ) return 0; /* A single table in the FROM clause */
if( pSrc->nSrc!=1 ) return 0;
if( pSrc->a[0].pSelect ) return 0; /* FROM clause is not a subquery */
pTab = pSrc->a[0].pTab;
if( pTab==0 ) return 0;
if( pTab->pSelect ) return 0; /* FROM clause is not a view */
if( IsVirtual(pTab) ) return 0; /* FROM clause not a virtual table */
pEList = p->pEList;
if( pEList->nExpr!=1 ) return 0; /* One column in the result set */
if( pEList->a[0].pExpr->op!=TK_COLUMN ) return 0; /* Result is a column */
return 1;
}
#endif /* SQLITE_OMIT_SUBQUERY */
/*
** 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
@@ -1621,14 +1660,8 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int mustBeUnique){
** 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)!=0 && !p->pPrior
&& !p->isDistinct && !p->isAgg && !p->pGroupBy
&& p->pSrc && p->pSrc->nSrc==1 && !p->pSrc->a[0].pSelect
&& p->pSrc->a[0].pTab && !p->pSrc->a[0].pTab->pSelect
&& p->pEList->nExpr==1 && p->pEList->a[0].pExpr->op==TK_COLUMN
&& !p->pLimit && !p->pOffset && !p->pWhere
){
p = pX->pSelect;
if( isCandidateForInOpt(p) ){
sqlite3 *db = pParse->db;
Index *pIdx;
Expr *pExpr = p->pEList->a[0].pExpr;