planner: fix stack overflow caused by folding constant

expression/constant_fold.go

@@ -117,7 +117,10 @@ func foldConstant(expr Expression) (Expression, bool) {
 					constArgs[i] = One
 				}
 			}
-			dummyScalarFunc := NewFunctionInternal(x.GetCtx(), x.FuncName.L, x.GetType(), constArgs...)
+			dummyScalarFunc, err := NewFunctionBase(x.GetCtx(), x.FuncName.L, x.GetType(), constArgs...)
+			if err != nil {
+				return expr, isDeferredConst
+			}
 			value, err := dummyScalarFunc.Eval(chunk.Row{})
 			if err != nil {
 				return expr, isDeferredConst

expression/integration_test.go

@@ -3875,3 +3875,25 @@ func (s *testIntegrationSuite) TestIssue9325(c *C) {
 	result = tk.MustQuery("select * from t where a < timestamp'2019-02-16 14:21:00'")
 	result.Check(testkit.Rows("2019-02-16 14:19:59", "2019-02-16 14:20:01"))
 }
+
+func (s *testIntegrationSuite) TestIssue10156(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	defer s.cleanEnv(c)
+
+	tk.MustExec("use test")
+	tk.MustExec("CREATE TABLE `t1` (`period_name` varchar(24) DEFAULT NULL ,`period_id` bigint(20) DEFAULT NULL ,`starttime` bigint(20) DEFAULT NULL)")
+	tk.MustExec("CREATE TABLE `t2` (`bussid` bigint(20) DEFAULT NULL,`ct` bigint(20) DEFAULT NULL)")
+	q := `
+select
+    a.period_name,
+    b.date8
+from
+    (select * from t1) a
+left join
+    (select bussid,date(from_unixtime(ct)) date8 from t2) b
+on 
+    a.period_id = b.bussid
+where 
+    datediff(b.date8, date(from_unixtime(a.starttime))) >= 0`
+	tk.MustQuery(q)
+}

expression/scalar_function.go

@@ -72,6 +72,15 @@ func (sf *ScalarFunction) MarshalJSON() ([]byte, error) {
 
 // NewFunction creates a new scalar function or constant.
 func NewFunction(ctx sessionctx.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error) {
+	return newFunctionImpl(ctx, true, funcName, retType, args...)
+}
+
+// NewFunctionBase creates a new scalar function or constant without constant fold
+func NewFunctionBase(ctx sessionctx.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error) {
+	return newFunctionImpl(ctx, false, funcName, retType, args...)
+}
+
+func newFunctionImpl(ctx sessionctx.Context, fold bool, funcName string, retType *types.FieldType, args ...Expression) (Expression, error) {
 	if retType == nil {
 		return nil, errors.Errorf("RetType cannot be nil for ScalarFunction.")
 	}
@@ -96,7 +105,10 @@ func NewFunction(ctx sessionctx.Context, funcName string, retType *types.FieldTy
 		RetType:  retType,
 		Function: f,
 	}
-	return FoldConstant(sf), nil
+	if fold {
+		return FoldConstant(sf), nil
+	}
+	return sf, nil
 }
 
 // NewFunctionInternal is similar to NewFunction, but do not returns error, should only be used internally.