executor: avoid distsql request for TableReader/IndexReader/IndexLookup on temporary table

executor/distsql.go

@@ -196,6 +196,10 @@ type IndexReaderExecutor struct {
 
 // Close clears all resources hold by current object.
 func (e *IndexReaderExecutor) Close() error {
+	if e.table != nil && e.table.Meta().TempTableType != model.TempTableNone {
+		return nil
+	}
+
 	err := e.result.Close()
 	e.result = nil
 	e.ctx.StoreQueryFeedback(e.feedback)
@@ -204,6 +208,11 @@ func (e *IndexReaderExecutor) Close() error {
 
 // Next implements the Executor Next interface.
 func (e *IndexReaderExecutor) Next(ctx context.Context, req *chunk.Chunk) error {
+	if e.table != nil && e.table.Meta().TempTableType != model.TempTableNone {
+		req.Reset()
+		return nil
+	}
+
 	err := e.result.Next(ctx, req)
 	if err != nil {
 		e.feedback.Invalidate()
@@ -266,6 +275,11 @@ func (e *IndexReaderExecutor) open(ctx context.Context, kvRanges []kv.KeyRange)
 		e.dagPB.CollectExecutionSummaries = &collExec
 	}
 	e.kvRanges = kvRanges
+	// Treat temporary table as dummy table, avoid sending distsql request to TiKV.
+	// In a test case IndexReaderExecutor is mocked and e.table is nil.
+	if e.table != nil && e.table.Meta().TempTableType != model.TempTableNone {
+		return nil
+	}
 
 	e.memTracker = memory.NewTracker(e.id, -1)
 	e.memTracker.AttachTo(e.ctx.GetSessionVars().StmtCtx.MemTracker)
@@ -381,6 +395,12 @@ func (e *IndexLookUpExecutor) Open(ctx context.Context) error {
 		e.feedback.Invalidate()
 		return err
 	}
+
+	// Treat temporary table as dummy table, avoid sending distsql request to TiKV.
+	if e.table.Meta().TempTableType == model.TempTableGlobal {
+		return nil
+	}
+
 	err = e.open(ctx)
 	if err != nil {
 		e.feedback.Invalidate()
@@ -639,6 +659,10 @@ func (e *IndexLookUpExecutor) buildTableReader(ctx context.Context, task *lookup
 
 // Close implements Exec Close interface.
 func (e *IndexLookUpExecutor) Close() error {
+	if e.table.Meta().TempTableType != model.TempTableNone {
+		return nil
+	}
+
 	if !e.workerStarted || e.finished == nil {
 		return nil
 	}
@@ -659,6 +683,11 @@ func (e *IndexLookUpExecutor) Close() error {
 
 // Next implements Exec Next interface.
 func (e *IndexLookUpExecutor) Next(ctx context.Context, req *chunk.Chunk) error {
+	if e.table.Meta().TempTableType == model.TempTableGlobal {
+		req.Reset()
+		return nil
+	}
+
 	if !e.workerStarted {
 		if err := e.startWorkers(ctx, req.RequiredRows()); err != nil {
 			return err

executor/executor_test.go

@@ -8316,6 +8316,52 @@ func (s testSerialSuite) TestExprBlackListForEnum(c *C) {
 	c.Assert(checkFuncPushDown(rows, "index:idx(b, a)"), IsTrue)
 }
 
+func (s testSerialSuite) TestTemporaryTableNoNetwork(c *C) {
+	// Test that table reader/index reader/index lookup on the temporary table do not need to visit TiKV.
+	tk := testkit.NewTestKit(c, s.store)
+
+	tk.MustExec("use test")
+	tk.MustExec("create table normal (id int, a int, index(a))")
+	tk.MustExec("create global temporary table tmp_t (id int, a int, index(a)) on commit delete rows")
+
+	tk.MustExec("begin")
+	tk.MustExec("insert into tmp_t values (1, 1)")
+	tk.MustExec("insert into tmp_t values (2, 2)")
+
+	c.Assert(failpoint.Enable("github.com/pingcap/tidb/store/mockstore/unistore/rpcServerBusy", "return(true)"), IsNil)
+	defer func() {
+		c.Assert(failpoint.Disable("github.com/pingcap/tidb/store/mockstore/unistore/rpcServerBusy"), IsNil)
+	}()
+
+	// Make sure the fail point works.
+	// With that failpoint, all requests to the TiKV is discard.
+	rs, err := tk.Exec("select * from normal")
+	c.Assert(err, IsNil)
+	blocked := make(chan struct{})
+	ctx, cancelFunc := context.WithCancel(context.Background())
+	go func() {
+		_, err := session.ResultSetToStringSlice(ctx, tk.Se, rs)
+		blocked <- struct{}{}
+		c.Assert(err, NotNil)
+	}()
+	select {
+	case <-blocked:
+		c.Error("The query should block when the failpoint is enabled")
+	case <-time.After(200 * time.Millisecond):
+	}
+	cancelFunc()
+
+	// Check the temporary table do not send request to TiKV.
+	// Table reader
+	tk.MustQuery("select * from tmp_t").Check(testkit.Rows("1 1", "2 2"))
+	// Index reader
+	tk.MustQuery("select /*+ USE_INDEX(tmp_t, a) */ a from tmp_t").Check(testkit.Rows("1", "2"))
+	// Index lookup
+	tk.MustQuery("select id from tmp_t where a = 1").Check(testkit.Rows("1"))
+
+	tk.MustExec("rollback")
+}
+
 func (s *testResourceTagSuite) TestResourceGroupTag(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")

executor/table_reader.go

@@ -153,6 +153,25 @@ func (e *TableReaderExecutor) Open(ctx context.Context) error {
 		}
 	}
 	firstPartRanges, secondPartRanges := distsql.SplitRangesAcrossInt64Boundary(e.ranges, e.keepOrder, e.desc, e.table.Meta() != nil && e.table.Meta().IsCommonHandle)
+
+	// Treat temporary table as dummy table, avoid sending distsql request to TiKV.
+	// Calculate the kv ranges here, UnionScan rely on this kv ranges.
+	if e.table.Meta() != nil && e.table.Meta().TempTableType != model.TempTableNone {
+		kvReq, err := e.buildKVReq(ctx, firstPartRanges)
+		if err != nil {
+			return err
+		}
+		e.kvRanges = append(e.kvRanges, kvReq.KeyRanges...)
+		if len(secondPartRanges) != 0 {
+			kvReq, err = e.buildKVReq(ctx, secondPartRanges)
+			if err != nil {
+				return err
+			}
+			e.kvRanges = append(e.kvRanges, kvReq.KeyRanges...)
+		}
+		return nil
+	}
+
 	firstResult, err := e.buildResp(ctx, firstPartRanges)
 	if err != nil {
 		e.feedback.Invalidate()
@@ -175,6 +194,12 @@ func (e *TableReaderExecutor) Open(ctx context.Context) error {
 // Next fills data into the chunk passed by its caller.
 // The task was actually done by tableReaderHandler.
 func (e *TableReaderExecutor) Next(ctx context.Context, req *chunk.Chunk) error {
+	if e.table.Meta() != nil && e.table.Meta().TempTableType != model.TempTableNone {
+		// Treat temporary table as dummy table, avoid sending distsql request to TiKV.
+		req.Reset()
+		return nil
+	}
+
 	logutil.Eventf(ctx, "table scan table: %s, range: %v", stringutil.MemoizeStr(func() string {
 		var tableName string
 		if meta := e.table.Meta(); meta != nil {
@@ -197,6 +222,10 @@ func (e *TableReaderExecutor) Next(ctx context.Context, req *chunk.Chunk) error
 
 // Close implements the Executor Close interface.
 func (e *TableReaderExecutor) Close() error {
+	if e.table.Meta() != nil && e.table.Meta().TempTableType != model.TempTableNone {
+		return nil
+	}
+
 	var err error
 	if e.resultHandler != nil {
 		err = e.resultHandler.Close()
@@ -209,6 +238,20 @@ func (e *TableReaderExecutor) Close() error {
 // buildResp first builds request and sends it to tikv using distsql.Select. It uses SelectResult returned by the callee
 // to fetch all results.
 func (e *TableReaderExecutor) buildResp(ctx context.Context, ranges []*ranger.Range) (distsql.SelectResult, error) {
+	kvReq, err := e.buildKVReq(ctx, ranges)
+	if err != nil {
+		return nil, err
+	}
+	e.kvRanges = append(e.kvRanges, kvReq.KeyRanges...)
+
+	result, err := e.SelectResult(ctx, e.ctx, kvReq, retTypes(e), e.feedback, getPhysicalPlanIDs(e.plans), e.id)
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+func (e *TableReaderExecutor) buildKVReq(ctx context.Context, ranges []*ranger.Range) (*kv.Request, error) {
 	var builder distsql.RequestBuilder
 	var reqBuilder *distsql.RequestBuilder
 	if e.kvRangeBuilder != nil {
@@ -231,17 +274,7 @@ func (e *TableReaderExecutor) buildResp(ctx context.Context, ranges []*ranger.Ra
 		SetMemTracker(e.memTracker).
 		SetStoreType(e.storeType).
 		SetAllowBatchCop(e.batchCop)
-	kvReq, err := reqBuilder.Build()
-	if err != nil {
-		return nil, err
-	}
-	e.kvRanges = append(e.kvRanges, kvReq.KeyRanges...)
-
-	result, err := e.SelectResult(ctx, e.ctx, kvReq, retTypes(e), e.feedback, getPhysicalPlanIDs(e.plans), e.id)
-	if err != nil {
-		return nil, err
-	}
-	return result, nil
+	return reqBuilder.Build()
 }
 
 func buildVirtualColumnIndex(schema *expression.Schema, columns []*model.ColumnInfo) []int {