From 1708905bff1dd422347bfbbf6efc0d3347266bc9 Mon Sep 17 00:00:00 2001
From: Zhuhe Fang <fzhedu@gmail.com>
Date: Thu, 16 Apr 2020 22:27:16 +0800
Subject: [PATCH] cherry pick #16444 to release-2.1

Signed-off-by: sre-bot <sre-bot@pingcap.com>
---
 planner/core/logical_plan_test.go        | 69 ++++++++++++++++++++++++
 planner/core/rule_predicate_push_down.go |  4 ++
 2 files changed, 73 insertions(+)

diff --git a/planner/core/logical_plan_test.go b/planner/core/logical_plan_test.go
index f136ca14d876a..b2b9b80081093 100644
--- a/planner/core/logical_plan_test.go
+++ b/planner/core/logical_plan_test.go
@@ -2215,3 +2215,72 @@ func (s *testPlanSuite) TestFastPlanContextTables(c *C) {
 		}
 	}
 }
+<<<<<<< HEAD
+=======
+
+func (s *testPlanSuite) TestUpdateEQCond(c *C) {
+	defer testleak.AfterTest(c)()
+	tests := []struct {
+		sql  string
+		best string
+	}{
+		{
+			sql:  "select t1.a from t t1, t t2 where t1.a = t2.a+1",
+			best: "Join{DataScan(t1)->DataScan(t2)->Projection}(test.t.a,Column#25)->Projection",
+		},
+	}
+	ctx := context.TODO()
+	for i, tt := range tests {
+		comment := Commentf("case:%v sql:%s", i, tt.sql)
+		stmt, err := s.ParseOneStmt(tt.sql, "", "")
+		c.Assert(err, IsNil, comment)
+		Preprocess(s.ctx, stmt, s.is)
+		builder := NewPlanBuilder(MockContext(), s.is, &hint.BlockHintProcessor{})
+		p, err := builder.Build(ctx, stmt)
+		c.Assert(err, IsNil)
+		p, err = logicalOptimize(ctx, builder.optFlag, p.(LogicalPlan))
+		c.Assert(err, IsNil)
+		c.Assert(ToString(p), Equals, tt.best, comment)
+	}
+}
+
+func (s *testPlanSuite) TestConflictedJoinTypeHints(c *C) {
+	defer testleak.AfterTest(c)()
+	sql := "select /*+ INL_JOIN(t1) HASH_JOIN(t1) */ * from t t1, t t2 where t1.e = t2.e"
+	ctx := context.TODO()
+	stmt, err := s.ParseOneStmt(sql, "", "")
+	c.Assert(err, IsNil)
+	Preprocess(s.ctx, stmt, s.is)
+	builder := NewPlanBuilder(MockContext(), s.is, &hint.BlockHintProcessor{})
+	p, err := builder.Build(ctx, stmt)
+	c.Assert(err, IsNil)
+	p, err = logicalOptimize(ctx, builder.optFlag, p.(LogicalPlan))
+	c.Assert(err, IsNil)
+	proj, ok := p.(*LogicalProjection)
+	c.Assert(ok, IsTrue)
+	join, ok := proj.Children()[0].(*LogicalJoin)
+	c.Assert(ok, IsTrue)
+	c.Assert(join.hintInfo, IsNil)
+	c.Assert(join.preferJoinType, Equals, uint(0))
+}
+
+func (s *testPlanSuite) TestSimplyOuterJoinWithOnlyOuterExpr(c *C) {
+	defer testleak.AfterTest(c)()
+	sql := "select * from t t1 right join t t0 ON TRUE where CONCAT_WS(t0.e=t0.e, 0, NULL) IS NULL"
+	ctx := context.TODO()
+	stmt, err := s.ParseOneStmt(sql, "", "")
+	c.Assert(err, IsNil)
+	Preprocess(s.ctx, stmt, s.is)
+	builder := NewPlanBuilder(MockContext(), s.is, &hint.BlockHintProcessor{})
+	p, err := builder.Build(ctx, stmt)
+	c.Assert(err, IsNil)
+	p, err = logicalOptimize(ctx, builder.optFlag, p.(LogicalPlan))
+	c.Assert(err, IsNil)
+	proj, ok := p.(*LogicalProjection)
+	c.Assert(ok, IsTrue)
+	join, ok := proj.Children()[0].(*LogicalJoin)
+	c.Assert(ok, IsTrue)
+	// previous wrong JoinType is InnerJoin
+	c.Assert(join.JoinType, Equals, RightOuterJoin)
+}
+>>>>>>> e3b635e... planner: cannot simply outer join if a predicate just refers to the outer table (#16444)
diff --git a/planner/core/rule_predicate_push_down.go b/planner/core/rule_predicate_push_down.go
index 1bd34b3425804..1fddcc2875b66 100644
--- a/planner/core/rule_predicate_push_down.go
+++ b/planner/core/rule_predicate_push_down.go
@@ -297,6 +297,10 @@ func simplifyOuterJoin(p *LogicalJoin, predicates []expression.Expression) {
 	// then simplify embedding outer join.
 	canBeSimplified := false
 	for _, expr := range predicates {
+		// avoid the case where the expr only refers to the schema of outerTable
+		if expression.ExprFromSchema(expr, outerTable.Schema()) {
+			continue
+		}
 		isOk := isNullRejected(p.ctx, innerTable.Schema(), expr)
 		if isOk {
 			canBeSimplified = true