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Make sure that the use of a double-quoted string literal does not trick

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the optimizer into using a correlated subquery when a static
subquery would suffice. (CVS 2477)

FossilOrigin-Name: ef4059e3afa1a61a9e59df00cdfedc57d8df9fec
This commit is contained in:
drh
2005-05-23 15:06:39 +00:00
parent 0bb8f36d05
commit 15ccce1c0d
4 changed files with 69 additions and 18 deletions
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25
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 1.198 2005/04/22 02:38:38 drh Exp $
** $Id: expr.c,v 1.199 2005/05/23 15:06:39 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -790,7 +790,6 @@ static int lookupName(
SrcList *pSrcList = pNC->pSrcList;
ExprList *pEList = pNC->pEList;
pNC->nRef++;
/* assert( zTab==0 || pEList==0 ); */
if( pSrcList ){
for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){
@@ -898,9 +897,9 @@ static int lookupName(
pExpr->op = TK_AS;
pExpr->iColumn = j;
pExpr->pLeft = sqlite3ExprDup(pEList->a[j].pExpr);
sqliteFree(zCol);
cnt = 1;
assert( zTab==0 && zDb==0 );
return 0;
goto lookupname_end_2;
}
}
}
@@ -919,6 +918,9 @@ static int lookupName(
** Z is a string literal if it doesn't match any column names. In that
** case, we need to return right away and not make any changes to
** pExpr.
**
** Because no reference was made to outer contexts, the pNC->nRef
** fields are not changed in any context.
*/
if( cnt==0 && zTab==0 && pColumnToken->z[0]=='"' ){
sqliteFree(zCol);
@@ -965,20 +967,31 @@ lookupname_end:
*/
sqliteFree(zDb);
sqliteFree(zTab);
sqliteFree(zCol);
sqlite3ExprDelete(pExpr->pLeft);
pExpr->pLeft = 0;
sqlite3ExprDelete(pExpr->pRight);
pExpr->pRight = 0;
pExpr->op = TK_COLUMN;
lookupname_end_2:
sqliteFree(zCol);
if( cnt==1 ){
assert( pNC!=0 );
sqlite3AuthRead(pParse, pExpr, pNC->pSrcList);
if( pMatch && !pMatch->pSelect ){
pExpr->pTab = pMatch->pTab;
}
/* Increment the nRef value on all name contexts from TopNC up to
** the point where the name matched. */
for(;;){
assert( pTopNC!=0 );
pTopNC->nRef++;
if( pTopNC==pNC ) break;
pTopNC = pTopNC->pNext;
}
return 0;
} else {
return 1;
}
return cnt!=1;
}
/*