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Fix the query optimizer so that it correctly handles constant expressions

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in the ON clause of a LEFT JOIN.  Ticket #2403. (CVS 4049)

FossilOrigin-Name: 46fdd195483787eef209a9b8ad108eba147be6fa
This commit is contained in:
drh
2007-06-08 00:20:47 +00:00
parent 98640a3fa1
commit 0a168377ad
6 changed files with 89 additions and 18 deletions
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30
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 1.296 2007/05/30 10:36:47 danielk1977 Exp $
** $Id: expr.c,v 1.297 2007/06/08 00:20:48 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -831,11 +831,21 @@ static int walkSelectExpr(Select *p, int (*xFunc)(void *, Expr*), void *pArg){
** is constant. See sqlite3ExprIsConstant() for additional information.
*/
static int exprNodeIsConstant(void *pArg, Expr *pExpr){
int *pN = (int*)pArg;
/* If *pArg is 3 then any term of the expression that comes from
** the ON or USING clauses of a join disqualifies the expression
** from being considered constant. */
if( (*pN)==3 && ExprHasAnyProperty(pExpr, EP_FromJoin) ){
*pN = 0;
return 2;
}
switch( pExpr->op ){
/* Consider functions to be constant if all their arguments are constant
** and *pArg==2 */
case TK_FUNCTION:
if( *((int*)pArg)==2 ) return 0;
if( (*pN)==2 ) return 0;
/* Fall through */
case TK_ID:
case TK_COLUMN:
@@ -846,11 +856,11 @@ static int exprNodeIsConstant(void *pArg, Expr *pExpr){
case TK_SELECT:
case TK_EXISTS:
#endif
*((int*)pArg) = 0;
*pN = 0;
return 2;
case TK_IN:
if( pExpr->pSelect ){
*((int*)pArg) = 0;
*pN = 0;
return 2;
}
default:
@@ -872,6 +882,18 @@ int sqlite3ExprIsConstant(Expr *p){
return isConst;
}
/*
** Walk an expression tree. Return 1 if the expression is constant
** that does no originate from the ON or USING clauses of a join.
** Return 0 if it involves variables or function calls or terms from
** an ON or USING clause.
*/
int sqlite3ExprIsConstantNotJoin(Expr *p){
int isConst = 3;
walkExprTree(p, exprNodeIsConstant, &isConst);
return isConst!=0;
}
/*
** Walk an expression tree. Return 1 if the expression is constant
** or a function call with constant arguments. Return and 0 if there