executor: fix wrong result of delete multiple tables using left join (#33055)

close pingcap/tidb#31321

executor/delete.go

@@ -159,6 +159,9 @@ func (e *DeleteExec) doBatchDelete(ctx context.Context) error {
 func (e *DeleteExec) composeTblRowMap(tblRowMap tableRowMapType, colPosInfos []plannercore.TblColPosInfo, joinedRow []types.Datum) error {
 	// iterate all the joined tables, and got the copresonding rows in joinedRow.
 	for _, info := range colPosInfos {
+		if unmatchedOuterRow(info, joinedRow) {
+			continue
+		}
 		if tblRowMap[info.TblID] == nil {
 			tblRowMap[info.TblID] = kv.NewHandleMap()
 		}

executor/executor_test.go

@@ -8521,3 +8521,33 @@ func (s *testSuite1) TestBitColumnIn(c *C) {
 	tk.MustExec("insert into t values (65)")
 	tk.MustQuery("select * from t where id not in (-1,2)").Check(testkit.Rows("\x00A"))
 }
+
+func (s *testSuite) TestDeleteWithMulTbl(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+
+	// Delete multiple tables from left joined table.
+	// The result of left join is (3, null, null).
+	// Because rows in t2 are not matched, so no row will be deleted in t2.
+	// But row in t1 is matched, so it should be deleted.
+	tk.MustExec("use test;")
+	tk.MustExec("drop table if exists t1, t2;")
+	tk.MustExec("create table t1 (c1 int);")
+	tk.MustExec("create table t2 (c1 int primary key, c2 int);")
+	tk.MustExec("insert into t1 values(3);")
+	tk.MustExec("insert into t2 values(2, 2);")
+	tk.MustExec("insert into t2 values(0, 0);")
+	tk.MustExec("delete from t1, t2 using t1 left join t2 on t1.c1 = t2.c2;")
+	tk.MustQuery("select * from t1 order by c1;").Check(testkit.Rows())
+	tk.MustQuery("select * from t2 order by c1;").Check(testkit.Rows("0 0", "2 2"))
+
+	// Rows in both t1 and t2 are matched, so will be deleted even if it's null.
+	// NOTE: The null values are not generated by join.
+	tk.MustExec("drop table if exists t1, t2;")
+	tk.MustExec("create table t1 (c1 int);")
+	tk.MustExec("create table t2 (c2 int);")
+	tk.MustExec("insert into t1 values(null);")
+	tk.MustExec("insert into t2 values(null);")
+	tk.MustExec("delete from t1, t2 using t1 join t2 where t1.c1 is null;")
+	tk.MustQuery("select * from t1;").Check(testkit.Rows())
+	tk.MustQuery("select * from t2;").Check(testkit.Rows())
+}

executor/update.go

@@ -96,7 +96,7 @@ func (e *UpdateExec) prepare(row []types.Datum) (err error) {
 				break
 			}
 		}
-		if e.unmatchedOuterRow(content, row) {
+		if unmatchedOuterRow(content, row) {
 			updatable = false
 		}
 		e.tableUpdatable = append(e.tableUpdatable, updatable)
@@ -211,7 +211,7 @@ func (e *UpdateExec) exec(ctx context.Context, schema *expression.Schema, row, n
 // the inner handle field is filled with a NULL value.
 //
 // This fixes: https://github.com/pingcap/tidb/issues/7176.
-func (e *UpdateExec) unmatchedOuterRow(tblPos plannercore.TblColPosInfo, waitUpdateRow []types.Datum) bool {
+func unmatchedOuterRow(tblPos plannercore.TblColPosInfo, waitUpdateRow []types.Datum) bool {
 	firstHandleIdx := tblPos.HandleCols.GetCol(0)
 	return waitUpdateRow[firstHandleIdx.Index].IsNull()
 }