planner: provide a system view cluster_tidb_plan_cache to allow users to see the cluster's Plan Cache Info

pkg/executor/builder.go

@@ -2279,6 +2279,7 @@ func (b *executorBuilder) buildMemTable(v *plannercore.PhysicalMemTable) exec.Ex
 			strings.ToLower(infoschema.TableKeywords),
 			strings.ToLower(infoschema.TableTiDBIndexUsage),
 			strings.ToLower(infoschema.TableTiDBPlanCache),
+			strings.ToLower(infoschema.ClusterTableTiDBPlanCache),
 			strings.ToLower(infoschema.ClusterTableTiDBIndexUsage):
 			memTracker := memory.NewTracker(v.ID(), -1)
 			memTracker.AttachTo(b.ctx.GetSessionVars().StmtCtx.MemTracker)

pkg/executor/infoschema_reader.go

@@ -211,7 +211,9 @@ func (e *memtableRetriever) retrieve(ctx context.Context, sctx sessionctx.Contex
 		case infoschema.ClusterTableTiDBIndexUsage:
 			err = e.setDataFromClusterIndexUsage(ctx, sctx)
 		case infoschema.TableTiDBPlanCache:
-			err = e.setDataFromPlanCache(ctx, sctx)
+			err = e.setDataFromPlanCache(ctx, sctx, false)
+		case infoschema.ClusterTableTiDBPlanCache:
+			err = e.setDataFromPlanCache(ctx, sctx, true)
 		}
 		if err != nil {
 			return nil, err
@@ -3916,7 +3918,7 @@ func (e *memtableRetriever) setDataFromClusterIndexUsage(ctx context.Context, sc
 	return nil
 }
 
-func (e *memtableRetriever) setDataFromPlanCache(_ context.Context, sctx sessionctx.Context) error {
+func (e *memtableRetriever) setDataFromPlanCache(_ context.Context, sctx sessionctx.Context, cluster bool) (err error) {
 	values := domain.GetDomain(sctx).GetInstancePlanCache().All()
 	rows := make([][]types.Datum, 0, len(values))
 	for _, v := range values {
@@ -3946,6 +3948,12 @@ func (e *memtableRetriever) setDataFromPlanCache(_ context.Context, sctx session
 		rows = append(rows, row)
 	}
 
+	if cluster {
+		if rows, err = infoschema.AppendHostInfoToRows(sctx, rows); err != nil {
+			return err
+		}
+	}
+
 	e.rows = rows
 	return nil
 }

pkg/infoschema/cluster.go

@@ -54,6 +54,8 @@ const (
 	ClusterTableMemoryUsageOpsHistory = "CLUSTER_MEMORY_USAGE_OPS_HISTORY"
 	// ClusterTableTiDBIndexUsage is a table to show the usage stats of indexes across the whole cluster.
 	ClusterTableTiDBIndexUsage = "CLUSTER_TIDB_INDEX_USAGE"
+	// ClusterTableTiDBPlanCache is the plan cache status of tidb cluster.
+	ClusterTableTiDBPlanCache = "CLUSTER_TIDB_PLAN_CACHE"
 )
 
 // memTableToAllTiDBClusterTables means add memory table to cluster table that will send cop request to all TiDB nodes.
@@ -69,6 +71,7 @@ var memTableToAllTiDBClusterTables = map[string]string{
 	TableMemoryUsage:              ClusterTableMemoryUsage,
 	TableMemoryUsageOpsHistory:    ClusterTableMemoryUsageOpsHistory,
 	TableTiDBIndexUsage:           ClusterTableTiDBIndexUsage,
+	TableTiDBPlanCache:            ClusterTableTiDBPlanCache,
 }
 
 // memTableToDDLOwnerClusterTables means add memory table to cluster table that will send cop request to DDL owner node.

pkg/infoschema/tables.go

@@ -341,6 +341,7 @@ var tableIDMap = map[string]int64{
 	ClusterTableTiDBIndexUsage:           autoid.InformationSchemaDBID + 94,
 	TableTiFlashIndexes:                  autoid.InformationSchemaDBID + 95,
 	TableTiDBPlanCache:                   autoid.InformationSchemaDBID + 96,
+	ClusterTableTiDBPlanCache:            autoid.InformationSchemaDBID + 97,
 }
 
 // columnInfo represents the basic column information of all kinds of INFORMATION_SCHEMA tables

pkg/infoschema/test/clustertablestest/cluster_tables_test.go

@@ -1972,3 +1972,54 @@ func TestMDLViewIDConflict(t *testing.T) {
 	txnTK2.MustExec("COMMIT")
 	wg.Wait()
 }
+
+func TestPlanCacheView(t *testing.T) {
+	s := new(clusterTablesSuite)
+	s.store, s.dom = testkit.CreateMockStoreAndDomain(t)
+	s.rpcserver, s.listenAddr = s.setUpRPCService(t, "127.0.0.1:0", nil)
+	s.httpServer, s.mockAddr = s.setUpMockPDHTTPServer()
+	s.startTime = time.Now()
+	defer s.httpServer.Close()
+	defer s.rpcserver.Stop()
+
+	tk := s.newTestKitWithRoot(t)
+	tk.MustExec("use test")
+	tk.MustExec(`set global tidb_enable_instance_plan_cache=1`)
+	tk.MustExec(`create table t (a int)`)
+	tk.MustExec(`prepare st from 'select a from t where a<?'`)
+	tk.MustExec(`set @a=1`)
+	tk.MustExec(`execute st using @a`)
+	tk.MustExec(`set @a=2`)
+	tk.MustExec(`execute st using @a`)
+	tk.RefreshSession()
+
+	require.Eventually(t, func() bool {
+		result := tk.MustQuery(`select instance, sql_text, executions from information_schema.cluster_tidb_plan_cache`)
+		expectedResult := testkit.Rows(
+			":10080 select a from t where a<? 2")
+		if !result.Equal(expectedResult) {
+			logutil.BgLogger().Warn("result not equal", zap.Any("rows", result.Rows()))
+			return false
+		}
+		return true
+	}, time.Second*2, time.Millisecond*100)
+
+	tk.MustExec("use test")
+	tk.MustExec(`prepare st from 'select a from t where a in (?)'`)
+	tk.MustExec(`set @a=2`)
+	tk.MustExec(`execute st using @a`)
+	tk.MustExec(`execute st using @a`)
+	tk.MustExec(`execute st using @a`)
+	tk.RefreshSession()
+	require.Eventually(t, func() bool {
+		result := tk.MustQuery(`select instance, sql_text, executions from information_schema.cluster_tidb_plan_cache order by executions`)
+		expectedResult := testkit.Rows(
+			":10080 select a from t where a<? 2",
+			":10080 select a from t where a in (?) 3")
+		if !result.Equal(expectedResult) {
+			logutil.BgLogger().Warn("result not equal", zap.Any("rows", result.Rows()))
+			return false
+		}
+		return true
+	}, time.Second*2, time.Millisecond*100)
+}