database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-11-11 01:42:22 +03:00
Code Activity

Improved technique for parsing the ON and USING clauses of a join is faster

Browse Source 
and uses less memory.

FossilOrigin-Name: 158156a3e3d50042cafc75dea3aaaa68b1f2efb9c3d178518ea6e68e32e0d21c
This commit is contained in:
drh
2022-04-07 01:11:13 +00:00
parent 200adc9e75
commit d44f8b2385
16 changed files with 150 additions and 113 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
src/select.c
View File

@@ -468,7 +468,7 @@ static int sqliteProcessJoin(Parse *pParse, Select *p){
** every column that the two tables have in common.
*/
if( pRight->fg.jointype & JT_NATURAL ){
if( pRight->pOn || pRight->pUsing ){
if( pRight->fg.isUsing || pRight->u3.pOn ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
return 1;
@@ -487,23 +487,6 @@ static int sqliteProcessJoin(Parse *pParse, Select *p){
}
}
/* Disallow both ON and USING clauses in the same join
*/
if( pRight->pOn && pRight->pUsing ){
sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
"clauses in the same join");
return 1;
}
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
if( pRight->pOn ){
if( isOuter ) sqlite3SetJoinExpr(pRight->pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(pParse, p->pWhere, pRight->pOn);
pRight->pOn = 0;
}
/* Create extra terms on the WHERE clause for each column named
** in the USING clause. Example: If the two tables to be joined are
** A and B and the USING clause names X, Y, and Z, then add this
@@ -511,8 +494,9 @@ 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( pRight->pUsing ){
IdList *pList = pRight->pUsing;
if( pRight->fg.isUsing ){
IdList *pList = pRight->u3.pUsing;
assert( pList!=0 );
for(j=0; j<pList->nId; j++){
char *zName; /* Name of the term in the USING clause */
int iLeft; /* Table on the left with matching column name */
@@ -532,6 +516,15 @@ static int sqliteProcessJoin(Parse *pParse, Select *p){
isOuter, &p->pWhere);
}
}
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
else if( pRight->u3.pOn ){
if( isOuter ) sqlite3SetJoinExpr(pRight->u3.pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(pParse, p->pWhere, pRight->u3.pOn);
pRight->u3.pOn = 0;
}
}
return 0;
}
@@ -4222,7 +4215,7 @@ static int flattenSubquery(
pSubitem->zName = 0;
pSubitem->zAlias = 0;
pSubitem->pSelect = 0;
assert( pSubitem->pOn==0 );
assert( pSubitem->fg.isUsing!=0 || pSubitem->u3.pOn==0 );
/* If the sub-query is a compound SELECT statement, then (by restrictions
** 17 and 18 above) it must be a UNION ALL and the parent query must
@@ -4366,9 +4359,10 @@ static int flattenSubquery(
** outer query.
*/
for(i=0; i<nSubSrc; i++){
sqlite3IdListDelete(db, pSrc->a[i+iFrom].pUsing);
assert( pSrc->a[i+iFrom].fg.isTabFunc==0 );
pSrc->a[i+iFrom] = pSubSrc->a[i];
SrcItem *pItem = &pSrc->a[i+iFrom];
if( pItem->fg.isUsing ) sqlite3IdListDelete(db, pItem->u3.pUsing);
assert( pItem->fg.isTabFunc==0 );
*pItem = pSubSrc->a[i];
iNewParent = pSubSrc->a[i].iCursor;
memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
}
@@ -5092,7 +5086,7 @@ static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){
pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
if( pNew==0 ) return WRC_Abort;
memset(&dummy, 0, sizeof(dummy));
pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0,0);
pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0);
if( pNewSrc==0 ) return WRC_Abort;
*pNew = *p;
p->pSrc = pNewSrc;
@@ -5703,7 +5697,9 @@ static int selectExpander(Walker *pWalker, Select *p){
** table to the right of the join */
continue;
}
if( sqlite3IdListIndex(pFrom->pUsing, zName)>=0 ){
if( pFrom->fg.isUsing
&& sqlite3IdListIndex(pFrom->u3.pUsing, zName)>=0
){
/* In a join with a USING clause, omit columns in the
** using clause from the table on the right. */
continue;