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, 18 insertions, 8 deletions

diff --git a/src/expr.c b/src/expr.c
index 6ad789a3d..1b18828dd 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1877,18 +1877,30 @@ SrcList *sqlite3SrcListDup(sqlite3 *db, const SrcList *p, int flags){
     SrcItem *pNewItem = &pNew->a[i];
     const SrcItem *pOldItem = &p->a[i];
     Table *pTab;
-    if( pOldItem->fg.fixedSchema ){
+    pNewItem->fg = pOldItem->fg;
+    if( pOldItem->fg.isSubquery ){
+      Subquery *pNewSubq = sqlite3DbMallocRaw(db, sizeof(Subquery));
+      if( pNewSubq==0 ){
+        assert( db->mallocFailed );
+        pNewItem->fg.isSubquery = 0;
+      }else{
+        memcpy(pNewSubq, pOldItem->u4.pSubq, sizeof(*pNewSubq));
+        pNewSubq->pSelect = sqlite3SelectDup(db, pNewSubq->pSelect, flags);
+        if( pNewSubq->pSelect==0 ){
+          sqlite3DbFree(db, pNewSubq);
+          pNewSubq = 0;
+          pNewItem->fg.isSubquery = 0;
+        }
+      }
+      pNewItem->u4.pSubq = pNewSubq;
+    }else if( pOldItem->fg.fixedSchema ){
       pNewItem->u4.pSchema = pOldItem->u4.pSchema;
     }else{
       pNewItem->u4.zDatabase = sqlite3DbStrDup(db, pOldItem->u4.zDatabase);
     }
     pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
     pNewItem->zAlias = sqlite3DbStrDup(db, pOldItem->zAlias);
-    pNewItem->fg = pOldItem->fg;
     pNewItem->iCursor = pOldItem->iCursor;
-    pNewItem->sq.addrFillSub = pOldItem->sq.addrFillSub;
-    pNewItem->sq.regReturn = pOldItem->sq.regReturn;
-    pNewItem->sq.regResult = pOldItem->sq.regResult;
     if( pNewItem->fg.isIndexedBy ){
       pNewItem->u1.zIndexedBy = sqlite3DbStrDup(db, pOldItem->u1.zIndexedBy);
     }else if( pNewItem->fg.isTabFunc ){
@@ -1905,7 +1917,6 @@ SrcList *sqlite3SrcListDup(sqlite3 *db, const SrcList *p, int flags){
     if( pTab ){
       pTab->nTabRef++;
     }
-    pNewItem->sq.pSelect = sqlite3SelectDup(db, pOldItem->sq.pSelect, flags);
     if( pOldItem->fg.isUsing ){
       assert( pNewItem->fg.isUsing );
       pNewItem->u3.pUsing = sqlite3IdListDup(db, pOldItem->u3.pUsing);
@@ -1979,7 +1990,6 @@ Select *sqlite3SelectDup(sqlite3 *db, const Select *pDup, int flags){
     pp = &pNew->pPrior;
     pNext = pNew;
   }
-
   return pRet;
 }
 #else
@@ -2999,7 +3009,7 @@ static Select *isCandidateForInOpt(const Expr *pX){
   pSrc = p->pSrc;
   assert( pSrc!=0 );
   if( pSrc->nSrc!=1 ) return 0;          /* Single term in FROM clause */
-  if( pSrc->a[0].sq.pSelect ) return 0;  /* FROM is not a subquery or view */
+  if( pSrc->a[0].fg.isSubquery) return 0;/* FROM is not a subquery or view */
   pTab = pSrc->a[0].pSTab;
   assert( pTab!=0 );
   assert( !IsView(pTab)  );              /* FROM clause is not a view */