cherry pick pingcap#30231 to release-5.1

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

planner/core/integration_test.go

@@ -3993,6 +3993,12 @@ func (s *testIntegrationSuite) TestIssue26559(c *C) {
 
 func (s *testIntegrationSuite) TestIssue27797(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
+	origin := tk.MustQuery("SELECT @@session.tidb_partition_prune_mode")
+	originStr := origin.Rows()[0][0].(string)
+	defer func() {
+		tk.MustExec("set @@session.tidb_partition_prune_mode = '" + originStr + "'")
+	}()
+	tk.MustExec("set @@session.tidb_partition_prune_mode = 'static'")
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists t27797")
 	tk.MustExec("create table t27797(a int, b int, c int, d int) " +
@@ -4066,6 +4072,7 @@ func (s *testIntegrationSuite) TestIssues27130(c *C) {
 		"  └─TableFullScan 10000.00 cop[tikv] table:t1 keep order:false, stats:pseudo",
 	))
 
+<<<<<<< HEAD
 	tk.MustExec("drop table if exists t2")
 	tk.MustExec("create table t2( a enum('y','b','Abc','null'),b enum('y','b','Abc','null'),key(a, b));")
 	tk.MustQuery(`explain format='brief' select * from t2 where a like "A%"`).Check(testkit.Rows(
@@ -4078,6 +4085,34 @@ func (s *testIntegrationSuite) TestIssues27130(c *C) {
 		"└─Selection 8000.00 cop[tikv]  like(test.t2.a, \"A%\", 92), like(test.t2.b, \"A%\", 92)",
 		"  └─TableFullScan 10000.00 cop[tikv] table:t2 keep order:false, stats:pseudo",
 	))
+=======
+func (s *testIntegrationSuite) TestIssue29705(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	origin := tk.MustQuery("SELECT @@session.tidb_partition_prune_mode")
+	originStr := origin.Rows()[0][0].(string)
+	defer func() {
+		tk.MustExec("set @@session.tidb_partition_prune_mode = '" + originStr + "'")
+	}()
+	tk.MustExec("set @@session.tidb_partition_prune_mode = 'static'")
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(id int) partition by hash(id) partitions 4;")
+	tk.MustExec("insert into t values(1);")
+	result := tk.MustQuery("SELECT COUNT(1) FROM ( SELECT COUNT(1) FROM t b GROUP BY id) a;")
+	result.Check(testkit.Rows("1"))
+}
+
+func (s *testIntegrationSerialSuite) TestIssue30271(c *C) {
+	defer collate.SetNewCollationEnabledForTest(false)
+	collate.SetNewCollationEnabledForTest(true)
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a char(10), b char(10), c char(10), index (a, b, c)) collate utf8mb4_bin;")
+	tk.MustExec("insert into t values ('b', 'a', '1'), ('b', 'A', '2'), ('c', 'a', '3');")
+	tk.MustExec("set names utf8mb4 collate utf8mb4_general_ci;")
+	tk.MustQuery("select * from t where (a>'a' and b='a') or (b = 'A' and a < 'd') order by a,c;").Check(testkit.Rows("b a 1", "b A 2", "c a 3"))
+>>>>>>> 4785dc4a6... planner: fix inconsistent schema between UnionAll and child operator (#30231)
 
 	tk.MustExec("drop table if exists t3")
 	tk.MustExec("create table t3( a int,b enum('y','b','Abc','null'), c enum('y','b','Abc','null'),key(a, b, c));")

planner/core/rule_column_pruning.go

@@ -225,6 +225,23 @@ func (p *LogicalUnionAll) PruneColumns(parentUsedCols []*expression.Column) erro
 				p.schema.Columns = append(p.schema.Columns[:i], p.schema.Columns[i+1:]...)
 			}
 		}
+		// It's possible that the child operator adds extra columns to the schema.
+		// Currently, (*LogicalAggregation).PruneColumns() might do this.
+		// But we don't need such columns, so we add an extra Projection to prune this column when this happened.
+		for i, child := range p.Children() {
+			if p.schema.Len() < child.Schema().Len() {
+				schema := p.schema.Clone()
+				exprs := make([]expression.Expression, len(p.schema.Columns))
+				for j, col := range schema.Columns {
+					exprs[j] = col
+				}
+				proj := LogicalProjection{Exprs: exprs, AvoidColumnEvaluator: true}.Init(p.ctx, p.blockOffset)
+				proj.SetSchema(schema)
+
+				proj.SetChildren(child)
+				p.children[i] = proj
+			}
+		}
 	}
 	return nil
 }