From 86cd94afbad21e111ff768b8f7474a9489d38e87 Mon Sep 17 00:00:00 2001
From: tangenta <tangenta@126.com>
Date: Thu, 30 Jun 2022 16:50:39 +0800
Subject: [PATCH] planner: don't push down predicates over table dual (#35669)

close pingcap/tidb#35527
---
 planner/core/plan_test.go                | 11 +++++++++++
 planner/core/rule_predicate_push_down.go |  5 +++++
 2 files changed, 16 insertions(+)

diff --git a/planner/core/plan_test.go b/planner/core/plan_test.go
index ed05bcce2c429..e9ec780bbfd13 100644
--- a/planner/core/plan_test.go
+++ b/planner/core/plan_test.go
@@ -892,3 +892,14 @@ func TestIssue34863(t *testing.T) {
 	tk.MustQuery("select count(*) from c right join o on c.c_id=o.c_id;").Check(testkit.Rows("5"))
 	tk.MustQuery("select count(o.c_id) from c right join o on c.c_id=o.c_id;").Check(testkit.Rows("5"))
 }
+
+// https://github.com/pingcap/tidb/issues/35527.
+func TestTableDualAsSubQuery(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("CREATE VIEW v0(c0) AS SELECT NULL;")
+	tk.MustQuery("SELECT v0.c0 FROM v0 WHERE (v0.c0 IS NULL) LIKE(NULL);").Check(testkit.Rows())
+	tk.MustQuery("SELECT v0.c0 FROM (SELECT null as c0) v0 WHERE (v0.c0 IS NULL) like (NULL);").Check(testkit.Rows())
+}
diff --git a/planner/core/rule_predicate_push_down.go b/planner/core/rule_predicate_push_down.go
index d0b9553d55085..59a29d788d65a 100644
--- a/planner/core/rule_predicate_push_down.go
+++ b/planner/core/rule_predicate_push_down.go
@@ -417,6 +417,11 @@ func (p *LogicalProjection) PredicatePushDown(predicates []expression.Expression
 			return predicates, child
 		}
 	}
+	if len(p.children) == 1 {
+		if _, isDual := p.children[0].(*LogicalTableDual); isDual {
+			return predicates, p
+		}
+	}
 	for _, cond := range predicates {
 		newFilter := expression.ColumnSubstitute(cond, p.Schema(), p.Exprs)
 		if !expression.HasGetSetVarFunc(newFilter) {