Do not allow changes to sqlite3ExprIsTableConstant() that support pushdown of

subqueries interfere with the hash-join logic.

FossilOrigin-Name: 8682931f9c6b40e1b09139c10bbe932c38330b5eb0c5c84f2432ad19a6793e37

4 files changed, 23 insertions, 10 deletions

diff --git a/src/expr.c b/src/expr.c
index 9513e5ffd..0ccb39cc6 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -2570,14 +2570,22 @@ static int exprSelectWalkTableConstant(Walker *pWalker, Select *pSelect){
 ** expression must not refer to any non-deterministic function nor any
 ** table other than iCur.
 **
-** Enhanced on 2024-04-06:  Allow pExpr to contain uncorrelated subqueries.
+** Consider uncorrelated subqueries to be constants if the bAllowSubq
+** parameter is true.
 */
-static int sqlite3ExprIsTableConstant(Expr *p, int iCur){
+static int sqlite3ExprIsTableConstant(Expr *p, int iCur, int bAllowSubq){
   Walker w;
   w.eCode = 3;
   w.pParse = 0;
   w.xExprCallback = exprNodeIsConstant;
-  w.xSelectCallback = exprSelectWalkTableConstant;
+  if( bAllowSubq ){
+    w.xSelectCallback = exprSelectWalkTableConstant;
+  }else{
+    w.xSelectCallback = sqlite3SelectWalkFail;
+#ifdef SQLITE_DEBUG
+    w.xSelectCallback2 = sqlite3SelectWalkAssert2;
+#endif
+  }
   w.u.iCur = iCur;
   sqlite3WalkExpr(&w, p);
   return w.eCode;
@@ -2598,7 +2606,10 @@ static int sqlite3ExprIsTableConstant(Expr *p, int iCur){
 **
 **   (1)  pExpr cannot refer to any table other than pSrc->iCursor.
 **
-**   (2)  pExpr cannot use subqueries or non-deterministic functions.
+**   (2a) pExpr cannot use subqueries unless the bAllowSubq parameter is
+**        true and the subquery is non-correlated
+**
+**   (2b) pExpr cannot use non-deterministic functions.
 **
 **   (3)  pSrc cannot be part of the left operand for a RIGHT JOIN.
 **        (Is there some way to relax this constraint?)
@@ -2627,7 +2638,8 @@ static int sqlite3ExprIsTableConstant(Expr *p, int iCur){
 int sqlite3ExprIsSingleTableConstraint(
   Expr *pExpr,                 /* The constraint */
   const SrcList *pSrcList,     /* Complete FROM clause */
-  int iSrc                     /* Which element of pSrcList to use */
+  int iSrc,                    /* Which element of pSrcList to use */
+  int bAllowSubq               /* Allow non-correlated subqueries */
 ){
   const SrcItem *pSrc = &pSrcList->a[iSrc];
   if( pSrc->fg.jointype & JT_LTORJ ){
@@ -2652,7 +2664,8 @@ int sqlite3ExprIsSingleTableConstraint(
       }
     }
   }
-  return sqlite3ExprIsTableConstant(pExpr, pSrc->iCursor); /* rules (1), (2) */
+  /* Rules (1), (2a), and (2b) handled by the following: */
+  return sqlite3ExprIsTableConstant(pExpr, pSrc->iCursor, bAllowSubq);
 }
 
 
diff --git a/src/select.c b/src/select.c
index b20051851..b13aae1f9 100644
--- a/src/select.c
+++ b/src/select.c
@@ -5260,7 +5260,7 @@ static int pushDownWhereTerms(
   }
 #endif
 
-  if( sqlite3ExprIsSingleTableConstraint(pWhere, pSrcList, iSrc) ){
+  if( sqlite3ExprIsSingleTableConstraint(pWhere, pSrcList, iSrc, 1) ){
     nChng++;
     pSubq->selFlags |= SF_PushDown;
     while( pSubq ){
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index a735c445e..d80a64609 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -5082,7 +5082,7 @@ int sqlite3ExprTruthValue(const Expr*);
 int sqlite3ExprIsConstant(Parse*,Expr*);
 int sqlite3ExprIsConstantOrFunction(Expr*, u8);
 int sqlite3ExprIsConstantOrGroupBy(Parse*, Expr*, ExprList*);
-int sqlite3ExprIsSingleTableConstraint(Expr*,const SrcList*,int);
+int sqlite3ExprIsSingleTableConstraint(Expr*,const SrcList*,int,int);
 #ifdef SQLITE_ENABLE_CURSOR_HINTS
 int sqlite3ExprContainsSubquery(Expr*);
 #endif
diff --git a/src/where.c b/src/where.c
index a1837b587..65b6ae2c9 100644
--- a/src/where.c
+++ b/src/where.c
@@ -942,7 +942,7 @@ static SQLITE_NOINLINE void constructAutomaticIndex(
     ** WHERE clause (or the ON clause of a LEFT join) that constrain which
     ** rows of the target table (pSrc) that can be used. */
     if( (pTerm->wtFlags & TERM_VIRTUAL)==0
-     && sqlite3ExprIsSingleTableConstraint(pExpr, pTabList, pLevel->iFrom)
+     && sqlite3ExprIsSingleTableConstraint(pExpr, pTabList, pLevel->iFrom, 0)
     ){
       pPartial = sqlite3ExprAnd(pParse, pPartial,
                                 sqlite3ExprDup(pParse->db, pExpr, 0));
@@ -1211,7 +1211,7 @@ static SQLITE_NOINLINE void sqlite3ConstructBloomFilter(
     for(pTerm=pWInfo->sWC.a; pTerm<pWCEnd; pTerm++){
       Expr *pExpr = pTerm->pExpr;
       if( (pTerm->wtFlags & TERM_VIRTUAL)==0
-       && sqlite3ExprIsSingleTableConstraint(pExpr, pTabList, iSrc)
+       && sqlite3ExprIsSingleTableConstraint(pExpr, pTabList, iSrc, 0)
       ){
         sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL);
       }