Proposed fix for a problem associated with OP_SeekScan that results in an

incorrect answer.  See ticket [5981a8c041a3c2f3].

FossilOrigin-Name: 266e9cbada531716c908c21d60a6038109722e3dd040237679ac0240fb5020ea

1 files changed, 12 insertions, 1 deletions

diff --git a/src/wherecode.c b/src/wherecode.c
index 4dc94f7fa..460ac4fe3 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -1884,8 +1884,19 @@ Bitmask sqlite3WhereCodeOneLoopStart(
     ** range (if any).
     */
     nConstraint = nEq;
+    assert( pLevel->p2==0 );
     if( pRangeEnd ){
       Expr *pRight = pRangeEnd->pExpr->pRight;
+      if( addrSeekScan ){
+        /* For a seek-scan that has a range on the lowest term of the index,
+        ** we have to make the top of the loop be code that sets the end
+        ** condition of the range.  Otherwise, the OP_SeekScan might jump
+        ** over that initialization, leaving the range-end value set to the
+        ** range-start value, resulting in a wrong answer.
+        ** See ticket 5981a8c041a3c2f3 (2021-11-02).
+        */
+        pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+      }
       codeExprOrVector(pParse, pRight, regBase+nEq, nTop);
       whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
       if( (pRangeEnd->wtFlags & TERM_VNULL)==0
@@ -1919,7 +1930,7 @@ Bitmask sqlite3WhereCodeOneLoopStart(
     sqlite3DbFree(db, zEndAff);
 
     /* Top of the loop body */
-    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+    if( pLevel->p2==0 ) pLevel->p2 = sqlite3VdbeCurrentAddr(v);
 
     /* Check if the index cursor is past the end of the range. */
     if( nConstraint ){