Disable the push-down optimization for sub-queries that are INTERSECT, UNION or EXCEPT compounds. dbsqlfuzz a34f455c91ad75a0cf8cd9476841903f42930a7a.

FossilOrigin-Name: 346a3b12b861ce7ba369e98cd336f79a1d4f7a7bb9acd7a4f63f37b391755bf5

1 files changed, 11 insertions, 0 deletions

diff --git a/src/select.c b/src/select.c
index 42a476c00..0925f102e 100644
--- a/src/select.c
+++ b/src/select.c
@@ -5009,6 +5009,13 @@ static int pushDownWindowCheck(Parse *pParse, Select *pSubq, Expr *pExpr){
 **       be materialized.  (This restriction is implemented in the calling
 **       routine.)
 **
+**   (8) The subquery may not be a compound that uses UNION, INTERSECT,
+**       or EXCEPT.  (We could, perhaps, relax this restriction to allow
+**       this case if none of the comparisons operators between left and
+**       right arms of the compound use a collation other than BINARY.
+**       But it is a lot of work to check that case for an obscure and
+**       minor optimization, so we omit it for now.)
+**
 ** Return 0 if no changes are made and non-zero if one or more WHERE clause
 ** terms are duplicated into the subquery.
 */
@@ -5028,6 +5035,10 @@ static int pushDownWhereTerms(
   if( pSubq->pPrior ){
     Select *pSel;
     for(pSel=pSubq; pSel; pSel=pSel->pPrior){
+      u8 op = pSel->op;
+      assert( op==TK_ALL || op==TK_SELECT 
+           || op==TK_UNION || op==TK_INTERSECT || op==TK_EXCEPT );
+      if( op!=TK_ALL && op!=TK_SELECT ) return 0;  /* restriction (8) */
       if( pSel->pWin ) return 0;    /* restriction (6b) */
     }
   }else{