cherry pick pingcap#36613 to release-5.1

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

executor/infoschema_reader_test.go

@@ -945,3 +945,83 @@ func (s *testInfoschemaTableSuite) TestTablesPKType(c *C) {
 	tk.MustQuery("SELECT TIDB_PK_TYPE FROM information_schema.tables where table_schema = 'test' and table_name = 't_common'").Check(testkit.Rows("CLUSTERED"))
 	tk.MustQuery("SELECT TIDB_PK_TYPE FROM information_schema.tables where table_schema = 'INFORMATION_SCHEMA' and table_name = 'TABLES'").Check(testkit.Rows("NONCLUSTERED"))
 }
+<<<<<<< HEAD
+=======
+
+// https://github.com/pingcap/tidb/issues/32459.
+func TestJoinSystemTableContainsView(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t (a timestamp, b int);")
+	tk.MustExec("insert into t values (null, 100);")
+	tk.MustExec("create view v as select * from t;")
+	// This is used by grafana when TiDB is specified as the data source.
+	// See https://github.com/grafana/grafana/blob/e86b6662a187c77656f72bef3b0022bf5ced8b98/public/app/plugins/datasource/mysql/meta_query.ts#L31
+	for i := 0; i < 10; i++ {
+		tk.MustQuery(`
+SELECT
+    table_name as table_name,
+    ( SELECT
+        column_name as column_name
+      FROM information_schema.columns c
+      WHERE
+        c.table_schema = t.table_schema AND
+        c.table_name = t.table_name AND
+        c.data_type IN ('timestamp', 'datetime')
+      ORDER BY ordinal_position LIMIT 1
+    ) AS time_column,
+    ( SELECT
+        column_name AS column_name
+      FROM information_schema.columns c
+      WHERE
+        c.table_schema = t.table_schema AND
+        c.table_name = t.table_name AND
+        c.data_type IN('float', 'int', 'bigint')
+      ORDER BY ordinal_position LIMIT 1
+    ) AS value_column
+  FROM information_schema.tables t
+  WHERE
+    t.table_schema = database() AND
+    EXISTS
+    ( SELECT 1
+      FROM information_schema.columns c
+      WHERE
+        c.table_schema = t.table_schema AND
+        c.table_name = t.table_name AND
+        c.data_type IN ('timestamp', 'datetime')
+    ) AND
+    EXISTS
+    ( SELECT 1
+      FROM information_schema.columns c
+      WHERE
+        c.table_schema = t.table_schema AND
+        c.table_name = t.table_name AND
+        c.data_type IN('float', 'int', 'bigint')
+    )
+  LIMIT 1
+;
+`).Check(testkit.Rows("t a b"))
+	}
+}
+
+// https://github.com/pingcap/tidb/issues/36426.
+func TestShowColumnsWithSubQueryView(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+
+	tk.MustExec("CREATE TABLE added (`id` int(11), `name` text, `some_date` timestamp);")
+	tk.MustExec("CREATE TABLE incremental (`id` int(11), `name`text, `some_date` timestamp);")
+	tk.MustExec("create view temp_view as (select * from `added` where id > (select max(id) from `incremental`));")
+	// Show columns should not send coprocessor request to the storage.
+	require.NoError(t, failpoint.Enable("tikvclient/tikvStoreSendReqResult", `return("timeout")`))
+	tk.MustQuery("show columns from temp_view;").Check(testkit.Rows(
+		"id int(11) YES  <nil> ",
+		"name text YES  <nil> ",
+		"some_date timestamp YES  <nil> "))
+	require.NoError(t, failpoint.Disable("tikvclient/tikvStoreSendReqResult"))
+}
+>>>>>>> e39ef4cae... executor: prevent sending cop request for show columns (#36613)

executor/show.go

@@ -1729,7 +1729,12 @@ func (e *ShowExec) fetchShowBuiltins() error {
 func tryFillViewColumnType(ctx context.Context, sctx sessionctx.Context, is infoschema.InfoSchema, dbName model.CIStr, tbl *model.TableInfo) error {
 	if tbl.IsView() {
 		// Retrieve view columns info.
+<<<<<<< HEAD
 		planBuilder, _ := plannercore.NewPlanBuilder(sctx, is, &hint.BlockHintProcessor{})
+=======
+		planBuilder, _ := plannercore.NewPlanBuilder(
+			plannercore.PlanBuilderOptNoExecution{}).Init(s, is, &hint.BlockHintProcessor{})
+>>>>>>> e39ef4cae... executor: prevent sending cop request for show columns (#36613)
 		if viewLogicalPlan, err := planBuilder.BuildDataSourceFromView(ctx, dbName, tbl); err == nil {
 			viewSchema := viewLogicalPlan.Schema()
 			viewOutputNames := viewLogicalPlan.OutputNames()

planner/core/expression_rewriter.go

@@ -796,8 +796,14 @@ func (er *expressionRewriter) handleExistSubquery(ctx context.Context, v *ast.Ex
 		return v, true
 	}
 	np = er.popExistsSubPlan(np)
+<<<<<<< HEAD
 	if len(ExtractCorrelatedCols4LogicalPlan(np)) > 0 {
 		er.p, er.err = er.b.buildSemiApply(er.p, np, nil, er.asScalar, v.Not)
+=======
+
+	if er.b.disableSubQueryPreprocessing || len(ExtractCorrelatedCols4LogicalPlan(np)) > 0 {
+		er.p, er.err = er.b.buildSemiApply(er.p, np, nil, er.asScalar, v.Not, hasRewriteHint)
+>>>>>>> e39ef4cae... executor: prevent sending cop request for show columns (#36613)
 		if er.err != nil || !er.asScalar {
 			return v, true
 		}
@@ -969,7 +975,7 @@ func (er *expressionRewriter) handleScalarSubquery(ctx context.Context, v *ast.S
 		return v, true
 	}
 	np = er.b.buildMaxOneRow(np)
-	if len(ExtractCorrelatedCols4LogicalPlan(np)) > 0 {
+	if er.b.disableSubQueryPreprocessing || len(ExtractCorrelatedCols4LogicalPlan(np)) > 0 {
 		er.p = er.b.buildApplyWithJoinType(er.p, np, LeftOuterJoin)
 		if np.Schema().Len() > 1 {
 			newCols := make([]expression.Expression, 0, np.Schema().Len())

planner/core/planbuilder.go

@@ -508,6 +508,21 @@ type PlanBuilder struct {
 	isForUpdateRead             bool
 	allocIDForCTEStorage        int
 	buildingRecursivePartForCTE bool
+<<<<<<< HEAD
+=======
+	buildingCTE                 bool
+
+	// checkSemiJoinHint checks whether the SEMI_JOIN_REWRITE hint is possible to be applied on the current SELECT stmt.
+	// We need this variable for the hint since the hint is set in subquery, but we check its availability in its outer scope.
+	//   e.g. select * from t where exists(select /*+ SEMI_JOIN_REWRITE() */ 1 from t1 where t.a=t1.a)
+	// Whether the hint can be applied or not is checked after the subquery is fully built.
+	checkSemiJoinHint bool
+	// hasValidSemijoinHint would tell the outer APPLY/JOIN operator that there's valid hint to be checked later
+	// if there's SEMI_JOIN_REWRITE hint and we find checkSemiJoinHint is true.
+	hasValidSemiJoinHint bool
+	// disableSubQueryPreprocessing indicates whether to pre-process uncorrelated sub-queries in rewriting stage.
+	disableSubQueryPreprocessing bool
+>>>>>>> e39ef4cae... executor: prevent sending cop request for show columns (#36613)
 }
 
 type handleColHelper struct {
@@ -603,7 +618,39 @@ func (b *PlanBuilder) popSelectOffset() {
 	b.selectOffset = b.selectOffset[:len(b.selectOffset)-1]
 }
 
+<<<<<<< HEAD
 // NewPlanBuilder creates a new PlanBuilder. Return the original PlannerSelectBlockAsName as well, callers decide if
+=======
+// PlanBuilderOpt is used to adjust the plan builder.
+type PlanBuilderOpt interface {
+	Apply(builder *PlanBuilder)
+}
+
+// PlanBuilderOptNoExecution means the plan builder should not run any executor during Build().
+type PlanBuilderOptNoExecution struct{}
+
+// Apply implements the interface PlanBuilderOpt.
+func (p PlanBuilderOptNoExecution) Apply(builder *PlanBuilder) {
+	builder.disableSubQueryPreprocessing = true
+}
+
+// NewPlanBuilder creates a new PlanBuilder.
+func NewPlanBuilder(opts ...PlanBuilderOpt) *PlanBuilder {
+	builder := &PlanBuilder{
+		outerCTEs:           make([]*cteInfo, 0),
+		colMapper:           make(map[*ast.ColumnNameExpr]int),
+		handleHelper:        &handleColHelper{id2HandleMapStack: make([]map[int64][]HandleCols, 0)},
+		correlatedAggMapper: make(map[*ast.AggregateFuncExpr]*expression.CorrelatedColumn),
+	}
+	for _, opt := range opts {
+		opt.Apply(builder)
+	}
+	return builder
+}
+
+// Init initialize a PlanBuilder.
+// Return the original PlannerSelectBlockAsName as well, callers decide if
+>>>>>>> e39ef4cae... executor: prevent sending cop request for show columns (#36613)
 // PlannerSelectBlockAsName should be restored after using this builder.
 func NewPlanBuilder(sctx sessionctx.Context, is infoschema.InfoSchema, processor *hint.BlockHintProcessor) (*PlanBuilder, []ast.HintTable) {
 	savedBlockNames := sctx.GetSessionVars().PlannerSelectBlockAsName