Refactor the SrcItem object so that information about subqueries is stored

in a separately allocated Subquery object.  This reduces the memory requirements
for SrcItem and makes the code run faster.  It also provides an expansion path
for subquery processing that does not burden simple queries.  The current
checking mostly works, but there are still issues that need to be tracked
down and fixed.

FossilOrigin-Name: 8ff5dda8448d7e1a533d7f27db2573ce68fa9956b9d9847ced45e83c1f06bab0

1 files changed, 21 insertions, 8 deletions

diff --git a/src/resolve.c b/src/resolve.c
index 02a48d699..6dcb4e732 100644
--- a/src/resolve.c
+++ b/src/resolve.c
@@ -349,7 +349,7 @@ static int lookupName(
         pTab = pItem->pSTab;
         assert( pTab!=0 && pTab->zName!=0 );
         assert( pTab->nCol>0 || pParse->nErr );
-        assert( (int)pItem->fg.isNestedFrom == IsNestedFrom(pItem->sq.pSelect));
+        assert( (int)pItem->fg.isNestedFrom == IsNestedFrom(pItem));
         if( pItem->fg.isNestedFrom ){
           /* In this case, pItem is a subquery that has been formed from a
           ** parenthesized subset of the FROM clause terms.  Example:
@@ -358,8 +358,12 @@ static int lookupName(
           **             This pItem -------------^
           */
           int hit = 0;
-          assert( pItem->sq.pSelect!=0 );
-          pEList = pItem->sq.pSelect->pEList;
+          Select *pSel;
+          assert( pItem->fg.isSubquery );
+          assert( pItem->u4.pSubq!=0 );
+          pSel = pItem->u4.pSubq->pSelect;
+          assert( pSel!=0 );
+          pEList = pSel->pEList;
           assert( pEList!=0 );
           assert( pEList->nExpr==pTab->nCol );
           for(j=0; j<pEList->nExpr; j++){
@@ -1880,7 +1884,11 @@ static int resolveSelectStep(Walker *pWalker, Select *p){
     ** moves the pOrderBy down to the sub-query. It will be moved back
     ** after the names have been resolved.  */
     if( p->selFlags & SF_Converted ){
-      Select *pSub = p->pSrc->a[0].sq.pSelect;
+      Select *pSub;
+      assert( p->pSrc->a[0].fg.isSubquery );
+      assert( p->pSrc->a[0].u4.pSubq!=0 );
+      pSub = p->pSrc->a[0].u4.pSubq->pSelect;
+      assert( pSub!=0 );
       assert( p->pSrc->nSrc==1 && p->pOrderBy );
       assert( pSub->pPrior && pSub->pOrderBy==0 );
       pSub->pOrderBy = p->pOrderBy;
@@ -1893,13 +1901,15 @@ static int resolveSelectStep(Walker *pWalker, Select *p){
     for(i=0; i<p->pSrc->nSrc; i++){
       SrcItem *pItem = &p->pSrc->a[i];
       assert( pItem->zName!=0
-              || pItem->sq.pSelect!=0 );  /* Test of tag-20240424-1*/
-      if( pItem->sq.pSelect && (pItem->sq.pSelect->selFlags & SF_Resolved)==0 ){
+              || pItem->fg.isSubquery );  /* Test of tag-20240424-1*/
+      if( pItem->fg.isSubquery
+       && (pItem->u4.pSubq->pSelect->selFlags & SF_Resolved)==0
+      ){
         int nRef = pOuterNC ? pOuterNC->nRef : 0;
         const char *zSavedContext = pParse->zAuthContext;
 
         if( pItem->zName ) pParse->zAuthContext = pItem->zName;
-        sqlite3ResolveSelectNames(pParse, pItem->sq.pSelect, pOuterNC);
+        sqlite3ResolveSelectNames(pParse, pItem->u4.pSubq->pSelect, pOuterNC);
         pParse->zAuthContext = zSavedContext;
         if( pParse->nErr ) return WRC_Abort;
         assert( db->mallocFailed==0 );
@@ -2001,7 +2011,10 @@ static int resolveSelectStep(Walker *pWalker, Select *p){
     ** These integers will be replaced by copies of the corresponding result
     ** set expressions by the call to resolveOrderGroupBy() below.  */
     if( p->selFlags & SF_Converted ){
-      Select *pSub = p->pSrc->a[0].sq.pSelect;
+      Select *pSub;
+      assert( p->pSrc->a[0].fg.isSubquery );
+      pSub = p->pSrc->a[0].u4.pSubq->pSelect;
+      assert( pSub!=0 );
       p->pOrderBy = pSub->pOrderBy;
       pSub->pOrderBy = 0;
     }