planner, util: new unfixed mutrow for TypeNull (#17893)

planner/core/integration_test.go

@@ -408,3 +408,14 @@ func (s *testIntegrationSuite) TestTableDualWithRequiredProperty(c *C) {
 	tk.MustExec("create table t2 (a int, b int)")
 	tk.MustExec("select /*+ MERGE_JOIN(t1, t2) */ * from t1 partition (p0), t2  where t1.a > 100 and t1.a = t2.a")
 }
+
+func (s *testIntegrationSuite) TestIssue16935(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t0;")
+	tk.MustExec("CREATE TABLE t0(c0 INT);")
+	tk.MustExec("INSERT INTO t0(c0) VALUES (1), (1), (1), (1), (1), (1);")
+	tk.MustExec("CREATE definer='root'@'localhost' VIEW v0(c0) AS SELECT NULL FROM t0;")
+
+	tk.MustQuery("SELECT * FROM t0 LEFT JOIN v0 ON TRUE WHERE v0.c0 IS NULL;")
+}

util/chunk/codec.go

@@ -171,7 +171,7 @@ func getFixedLen(colType *types.FieldType) int {
 	case mysql.TypeFloat:
 		return 4
 	case mysql.TypeTiny, mysql.TypeShort, mysql.TypeInt24, mysql.TypeLong,
-		mysql.TypeLonglong, mysql.TypeDouble, mysql.TypeYear, mysql.TypeDuration, mysql.TypeNull:
+		mysql.TypeLonglong, mysql.TypeDouble, mysql.TypeYear, mysql.TypeDuration:
 		return 8
 	case mysql.TypeDate, mysql.TypeDatetime, mysql.TypeTimestamp:
 		return 16

util/chunk/mutrow.go

@@ -109,7 +109,7 @@ func zeroValForType(tp *types.FieldType) interface{} {
 func makeMutRowColumn(in interface{}) *column {
 	switch x := in.(type) {
 	case nil:
-		col := makeMutRowUint64Column(uint64(0))
+		col := makeMutRowBytesColumn(nil)
 		col.nullBitmap[0] = 0
 		return col
 	case int: