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Query optimizer enhancement: In "FROM a,b,c left join d" allow the C table

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to be reordered with A and B.  This used to be the case but the capability
was removed by (3203) and (3052) in response to ticket #1652.  This change
restores the capability. (CVS 3529)

FossilOrigin-Name: 7393c81b8cb9d4344ae744de9eabcb3af64f1db8
This commit is contained in:
drh
2006-12-16 16:25:15 +00:00
parent f0fa1c1b9f
commit 61dfc31d80
9 changed files with 212 additions and 86 deletions
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31
src/select.c
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@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.322 2006/10/13 15:34:17 drh Exp $
** $Id: select.c,v 1.323 2006/12/16 16:25:15 drh Exp $
*/
#include "sqliteInt.h"
@@ -301,8 +301,8 @@ static int sqliteProcessJoin(Parse *pParse, Select *p){
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
*/
if( pLeft->jointype & JT_NATURAL ){
if( pLeft->pOn || pLeft->pUsing ){
if( pRight->jointype & JT_NATURAL ){
if( pRight->pOn || pRight->pUsing ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
return 1;
@@ -320,7 +320,7 @@ static int sqliteProcessJoin(Parse *pParse, Select *p){
/* Disallow both ON and USING clauses in the same join
*/
if( pLeft->pOn && pLeft->pUsing ){
if( pRight->pOn && pRight->pUsing ){
sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
"clauses in the same join");
return 1;
@@ -329,10 +329,10 @@ static int sqliteProcessJoin(Parse *pParse, Select *p){
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
if( pLeft->pOn ){
setJoinExpr(pLeft->pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(p->pWhere, pLeft->pOn);
pLeft->pOn = 0;
if( pRight->pOn ){
setJoinExpr(pRight->pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(p->pWhere, pRight->pOn);
pRight->pOn = 0;
}
/* Create extra terms on the WHERE clause for each column named
@@ -342,8 +342,8 @@ static int sqliteProcessJoin(Parse *pParse, Select *p){
** Report an error if any column mentioned in the USING clause is
** not contained in both tables to be joined.
*/
if( pLeft->pUsing ){
IdList *pList = pLeft->pUsing;
if( pRight->pUsing ){
IdList *pList = pRight->pUsing;
for(j=0; j<pList->nId; j++){
char *zName = pList->a[j].zName;
if( columnIndex(pLeftTab, zName)<0 || columnIndex(pRightTab, zName)<0 ){
@@ -1309,13 +1309,13 @@ static int prepSelectStmt(Parse *pParse, Select *p){
if( i>0 ){
struct SrcList_item *pLeft = &pTabList->a[i-1];
if( (pLeft->jointype & JT_NATURAL)!=0 &&
if( (pLeft[1].jointype & JT_NATURAL)!=0 &&
columnIndex(pLeft->pTab, zName)>=0 ){
/* In a NATURAL join, omit the join columns from the
** table on the right */
continue;
}
if( sqlite3IdListIndex(pLeft->pUsing, zName)>=0 ){
if( sqlite3IdListIndex(pLeft[1].pUsing, zName)>=0 ){
/* In a join with a USING clause, omit columns in the
** using clause from the table on the right. */
continue;
@@ -2175,7 +2175,7 @@ static int flattenSubquery(
**
** which is not at all the same thing.
*/
if( pSubSrc->nSrc>1 && iFrom>0 && (pSrc->a[iFrom-1].jointype & JT_OUTER)!=0 ){
if( pSubSrc->nSrc>1 && (pSubitem->jointype & JT_OUTER)!=0 ){
return 0;
}
@@ -2192,8 +2192,7 @@ static int flattenSubquery(
** But the t2.x>0 test will always fail on a NULL row of t2, which
** effectively converts the OUTER JOIN into an INNER JOIN.
*/
if( iFrom>0 && (pSrc->a[iFrom-1].jointype & JT_OUTER)!=0
&& pSub->pWhere!=0 ){
if( (pSubitem->jointype & JT_OUTER)!=0 && pSub->pWhere!=0 ){
return 0;
}
@@ -2232,7 +2231,7 @@ static int flattenSubquery(
pSrc->a[i+iFrom] = pSubSrc->a[i];
memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
}
pSrc->a[iFrom+nSubSrc-1].jointype = jointype;
pSrc->a[iFrom].jointype = jointype;
}
/* Now begin substituting subquery result set expressions for