executor: fix random cte error under apply (#57294) (#59185)

close #55881

Author: ti-chi-bot

executor/cte.go

@@ -85,16 +85,16 @@ func (e *CTEExec) Open(ctx context.Context) (err error) {
 	defer e.producer.resTbl.Unlock()
 
 	if e.producer.checkAndUpdateCorColHashCode() {
-		e.producer.reset()
-		if err = e.producer.reopenTbls(); err != nil {
+		err = e.producer.reset()
+		if err != nil {
 			return err
 		}
 	}
 	if e.producer.openErr != nil {
 		return e.producer.openErr
 	}
-	if !e.producer.opened {
-		if err = e.producer.openProducer(ctx, e); err != nil {
+	if !e.producer.hasCTEResult() && !e.producer.executorOpened {
+		if err = e.producer.openProducerExecutor(ctx, e); err != nil {
 			return err
 		}
 	}
@@ -105,8 +105,14 @@ func (e *CTEExec) Open(ctx context.Context) (err error) {
 func (e *CTEExec) Next(ctx context.Context, req *chunk.Chunk) (err error) {
 	e.producer.resTbl.Lock()
 	defer e.producer.resTbl.Unlock()
-	if !e.producer.resTbl.Done() {
-		if err = e.producer.produce(ctx); err != nil {
+	if !e.producer.hasCTEResult() {
+		// in case that another CTEExec call close without generate CTE result.
+		if !e.producer.executorOpened {
+			if err = e.producer.openProducerExecutor(ctx, e); err != nil {
+				return err
+			}
+		}
+		if err = e.producer.genCTEResult(ctx); err != nil {
 			return err
 		}
 	}
@@ -128,18 +134,23 @@ func (e *CTEExec) Close() (firstErr error) {
 	func() {
 		e.producer.resTbl.Lock()
 		defer e.producer.resTbl.Unlock()
-		if !e.producer.closed {
+		if e.producer.executorOpened {
 			failpoint.Inject("mock_cte_exec_panic_avoid_deadlock", func(v failpoint.Value) {
 				if ok := v.(bool); ok {
 					panic("mock mem oom panic")
 				}
 			})
-			// closeProducer() only close seedExec and recursiveExec, will not touch resTbl.
-			// It means you can still read resTbl after call closeProducer().
-			// You can even call all three functions(openProducer/produce/closeProducer) in CTEExec.Next().
+			// closeProducerExecutor() only close seedExec and recursiveExec, will not touch resTbl.
+			// It means you can still read resTbl after call closeProducerExecutor().
+			// You can even call all three functions(openProducerExecutor/genCTEResult/closeProducerExecutor) in CTEExec.Next().
 			// Separating these three function calls is only to follow the abstraction of the volcano model.
-			err := e.producer.closeProducer()
+			err := e.producer.closeProducerExecutor()
 			firstErr = setFirstErr(firstErr, err, "close cte producer error")
+			if !e.producer.hasCTEResult() {
+				// CTE result is not generated, in this case, we reset it
+				err = e.producer.reset()
+				firstErr = setFirstErr(firstErr, err, "close cte producer error")
+			}
 		}
 	}()
 	err := e.baseExecutor.Close()
@@ -154,10 +165,10 @@ func (e *CTEExec) reset() {
 }
 
 type cteProducer struct {
-	// opened should be false when not open or open fail(a.k.a. openErr != nil)
-	opened   bool
-	produced bool
-	closed   bool
+	// executorOpened is used to indicate whether the executor(seedExec/recursiveExec) is opened.
+	// when executorOpened is true, the executor is opened, otherwise it means the executor is
+	// not opened or is already closed.
+	executorOpened bool
 
 	// cteProducer is shared by multiple operators, so if the first operator tries to open
 	// and got error, the second should return open error directly instead of open again.
@@ -196,14 +207,10 @@ type cteProducer struct {
 	corColHashCodes [][]byte
 }
 
-func (p *cteProducer) openProducer(ctx context.Context, cteExec *CTEExec) (err error) {
+func (p *cteProducer) openProducerExecutor(ctx context.Context, cteExec *CTEExec) (err error) {
 	defer func() {
 		p.openErr = err
-		if err == nil {
-			p.opened = true
-		} else {
-			p.opened = false
-		}
+		p.executorOpened = true
 	}()
 	if p.seedExec == nil {
 		return errors.New("seedExec for CTEExec is nil")
@@ -246,7 +253,7 @@ func (p *cteProducer) openProducer(ctx context.Context, cteExec *CTEExec) (err e
 	return nil
 }
 
-func (p *cteProducer) closeProducer() (firstErr error) {
+func (p *cteProducer) closeProducerExecutor() (firstErr error) {
 	err := p.seedExec.Close()
 	firstErr = setFirstErr(firstErr, err, "close seedExec err")
 	if p.recursiveExec != nil {
@@ -264,7 +271,7 @@ func (p *cteProducer) closeProducer() (firstErr error) {
 	// because ExplainExec still needs tracker to get mem usage info.
 	p.memTracker = nil
 	p.diskTracker = nil
-	p.closed = true
+	p.executorOpened = false
 	return
 }
 
@@ -331,7 +338,13 @@ func (p *cteProducer) nextChunkLimit(cteExec *CTEExec, req *chunk.Chunk) error {
 	return nil
 }
 
-func (p *cteProducer) produce(ctx context.Context) (err error) {
+func (p *cteProducer) hasCTEResult() bool {
+	return p.resTbl.Done()
+}
+
+// genCTEResult generates the result of CTE, and stores the result in resTbl.
+// This is a synchronous function, which means it will block until the result is generated.
+func (p *cteProducer) genCTEResult(ctx context.Context) (err error) {
 	if p.resTbl.Error() != nil {
 		return p.resTbl.Error()
 	}
@@ -524,14 +537,18 @@ func (p *cteProducer) setupTblsForNewIteration() (err error) {
 	return nil
 }
 
-func (p *cteProducer) reset() {
+func (p *cteProducer) reset() error {
 	p.curIter = 0
 	p.hashTbl = nil
-
-	p.opened = false
+	p.executorOpened = false
 	p.openErr = nil
-	p.produced = false
-	p.closed = false
+
+	// Normally we need to setup tracker after calling Reopen(),
+	// But reopen resTbl means we need to call genCTEResult() again, it will setup tracker.
+	if err := p.resTbl.Reopen(); err != nil {
+		return err
+	}
+	return p.iterInTbl.Reopen()
 }
 
 func (p *cteProducer) resetTracker() {
@@ -545,18 +562,6 @@ func (p *cteProducer) resetTracker() {
 	}
 }
 
-func (p *cteProducer) reopenTbls() (err error) {
-	if p.isDistinct {
-		p.hashTbl = newConcurrentMapHashTable()
-	}
-	// Normally we need to setup tracker after calling Reopen(),
-	// But reopen resTbl means we need to call produce() again, it will setup tracker.
-	if err := p.resTbl.Reopen(); err != nil {
-		return err
-	}
-	return p.iterInTbl.Reopen()
-}
-
 // Check if tbl meets the requirement of limit.
 func (p *cteProducer) limitDone(tbl cteutil.Storage) bool {
 	return p.hasLimit && uint64(tbl.NumRows()) >= p.limitEnd

executor/executor_issue_test.go

@@ -1332,3 +1332,25 @@ func TestIssue49902(t *testing.T) {
 	tk.MustQuery("SELECT count(`t`.`c`) FROM (`s`) JOIN `t` GROUP BY `t`.`c`;").Check(testkit.Rows("170"))
 	tk.MustExec("set @@tidb_max_chunk_size = default;")
 }
+
+func TestIssue55881(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+
+	tk.MustExec("use test;")
+	tk.MustExec("drop table if exists aaa;")
+	tk.MustExec("drop table if exists bbb;")
+	tk.MustExec("create table aaa(id int, value int);")
+	tk.MustExec("create table bbb(id int, value int);")
+	tk.MustExec("insert into aaa values(1,2),(2,3)")
+	tk.MustExec("insert into bbb values(1,2),(2,3),(3,4)")
+	// set tidb_executor_concurrency to 1 to let the issue happens with high probability.
+	tk.MustExec("set tidb_executor_concurrency=1;")
+
+	// this is a random issue, so run it 100 times to increase the probability of the issue.
+	for i := 0; i < 100; i++ {
+		tk.MustQuery("with cte as (select * from aaa) select id, (select id from (select * from aaa where aaa.id != bbb.id union all select * from cte union all select * from cte) d limit 1)," +
+			"(select max(value) from (select * from cte union all select * from cte union all select * from aaa where aaa.id > bbb.id)) from bbb;")
+	}
+}