Do not allow a term in the WHERE clause of the query to qualify a par…

…tial index on the right table of a LEFT JOIN. Ticket [7f39060a24b47353]
fd · Nov 30, 2019 · a31cd0c · a31cd0c
1 parent b9fc654
commit a31cd0c
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Showing 2 changed files with 34 additions and 3 deletions.
diff --git a/src/where.c b/src/where.c
@@ -2790,19 +2790,25 @@ static int indexMightHelpWithOrderBy(
 /* Check to see if a partial index with pPartIndexWhere can be used
 ** in the current query.  Return true if it can be and false if not.
 */
-static int whereUsablePartialIndex(int iTab, WhereClause *pWC, Expr *pWhere){
+static int whereUsablePartialIndex(
+  int iTab,             /* The table for which we want an index */
+  int isLeft,           /* True if iTab is the right table of a LEFT JOIN */
+  WhereClause *pWC,     /* The WHERE clause of the query */
+  Expr *pWhere          /* The WHERE clause from the partial index */
+){
   int i;
   WhereTerm *pTerm;
   Parse *pParse = pWC->pWInfo->pParse;
   while( pWhere->op==TK_AND ){
-    if( !whereUsablePartialIndex(iTab,pWC,pWhere->pLeft) ) return 0;
+    if( !whereUsablePartialIndex(iTab,isLeft,pWC,pWhere->pLeft) ) return 0;
     pWhere = pWhere->pRight;
   }
   if( pParse->db->flags & SQLITE_EnableQPSG ) pParse = 0;
   for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
     Expr *pExpr;
     pExpr = pTerm->pExpr;
     if( (!ExprHasProperty(pExpr, EP_FromJoin) || pExpr->iRightJoinTable==iTab)
+     && (isLeft==0 || ExprHasProperty(pExpr, EP_FromJoin))
      && sqlite3ExprImpliesExpr(pParse, pExpr, pWhere, iTab) 
     ){
       return 1;
@@ -2965,8 +2971,11 @@ static int whereLoopAddBtree(
   for(; rc==SQLITE_OK && pProbe; 
       pProbe=(pSrc->pIBIndex ? 0 : pProbe->pNext), iSortIdx++
   ){
+    int isLeft = (pSrc->fg.jointype & JT_OUTER)!=0;
     if( pProbe->pPartIdxWhere!=0
-     && !whereUsablePartialIndex(pSrc->iCursor, pWC, pProbe->pPartIdxWhere) ){
+     && !whereUsablePartialIndex(pSrc->iCursor, isLeft, pWC,
+                                 pProbe->pPartIdxWhere)
+    ){
       testcase( pNew->iTab!=pSrc->iCursor );  /* See ticket [98d973b8f5] */
       continue;  /* Partial index inappropriate for this query */
     }

diff --git a/test/join.test b/test/join.test
@@ -953,4 +953,26 @@ do_execsql_test join-20.2 {
   SELECT * FROM t0 LEFT JOIN t1 WHERE NULL IN (c1);
 } {}
 
+# 2019-11-30 ticket 7f39060a24b47353
+# Do not allow a WHERE clause term to qualify a partial index on the
+# right table of a LEFT JOIN.
+#
+do_execsql_test join-21.10 {
+  DROP TABLE t0;
+  DROP TABLE t1;
+  CREATE TABLE t0(aa);
+  CREATE TABLE t1(bb);
+  INSERT INTO t0(aa) VALUES (1);
+  INSERT INTO t1(bb) VALUES (1);
+  SELECT 11, * FROM t1 LEFT JOIN t0 WHERE aa ISNULL;
+  SELECT 12, * FROM t1 LEFT JOIN t0 WHERE +aa ISNULL;
+  SELECT 13, * FROM t1 LEFT JOIN t0 ON aa ISNULL;
+  SELECT 14, * FROM t1 LEFT JOIN t0 ON +aa ISNULL;
+  CREATE INDEX i0 ON t0(aa) WHERE aa ISNULL;
+  SELECT 21, * FROM t1 LEFT JOIN t0 WHERE aa ISNULL;
+  SELECT 22, * FROM t1 LEFT JOIN t0 WHERE +aa ISNULL;
+  SELECT 23, * FROM t1 LEFT JOIN t0 ON aa ISNULL;
+  SELECT 24, * FROM t1 LEFT JOIN t0 ON +aa ISNULL;
+} {13 1 {} 14 1 {} 23 1 {} 24 1 {}}
+
 finish_test