ddl: avoid commit conflicts when updating/delete from mysql.tidb_ddl_reorg.

ddl/backfilling.go

@@ -146,7 +146,7 @@ func GetLeaseGoTime(currTime time.Time, lease time.Duration) types.Time {
 // Backfilling is time consuming, to accelerate this process, TiDB has built some sub
 // workers to do this in the DDL owner node.
 //
-//                                DDL owner thread
+//                       DDL owner thread (also see comments before runReorgJob func)
 //                                      ^
 //                                      | (reorgCtx.doneCh)
 //                                      |
@@ -583,9 +583,10 @@ func (dc *ddlCtx) sendTasksAndWait(scheduler *backfillScheduler, totalAddedCount
 		err = dc.isReorgRunnable(reorgInfo.Job.ID)
 	}
 
+	// Update the reorg handle that has been processed.
+	err1 := reorgInfo.UpdateReorgMeta(nextKey, scheduler.sessPool)
+
 	if err != nil {
-		// Update the reorg handle that has been processed.
-		err1 := reorgInfo.UpdateReorgMeta(nextKey, scheduler.sessPool)
 		metrics.BatchAddIdxHistogram.WithLabelValues(metrics.LblError).Observe(elapsedTime.Seconds())
 		logutil.BgLogger().Warn("[ddl] backfill worker handle batch tasks failed",
 
@@ -614,7 +615,8 @@ func (dc *ddlCtx) sendTasksAndWait(scheduler *backfillScheduler, totalAddedCount
 		zap.String("start key", hex.EncodeToString(startKey)),
 		zap.String("next key", hex.EncodeToString(nextKey)),
 		zap.Int64("batch added count", taskAddedCount),
-		zap.String("take time", elapsedTime.String()))
+		zap.String("take time", elapsedTime.String()),
+		zap.NamedError("updateHandleError", err1))
 	return nil
 }
 
@@ -1320,15 +1322,15 @@ func GetMaxBackfillJob(sess *session, jobID, currEleID int64, currEleKey []byte)
 }
 
 // MoveBackfillJobsToHistoryTable moves backfill table jobs to the backfill history table.
-func MoveBackfillJobsToHistoryTable(sessCtx sessionctx.Context, bfJob *BackfillJob) error {
-	sess, ok := sessCtx.(*session)
+func MoveBackfillJobsToHistoryTable(sctx sessionctx.Context, bfJob *BackfillJob) error {
+	s, ok := sctx.(*session)
 	if !ok {
-		return errors.Errorf("sess ctx:%#v convert session failed", sessCtx)
+		return errors.Errorf("sess ctx:%#v convert session failed", sctx)
 	}
 
-	return runInTxn(sess, func(se *session) error {
+	return s.runInTxn(func(se *session) error {
 		// TODO: Consider batch by batch update backfill jobs and insert backfill history jobs.
-		bJobs, err := GetBackfillJobs(sess, BackfillTable, fmt.Sprintf("ddl_job_id = %d and ele_id = %d and ele_key = '%s'",
+		bJobs, err := GetBackfillJobs(se, BackfillTable, fmt.Sprintf("ddl_job_id = %d and ele_id = %d and ele_key = '%s'",
 			bfJob.JobID, bfJob.EleID, bfJob.EleKey), "update_backfill_job")
 		if err != nil {
 			return errors.Trace(err)
@@ -1342,13 +1344,13 @@ func MoveBackfillJobsToHistoryTable(sessCtx sessionctx.Context, bfJob *BackfillJ
 			return errors.Trace(err)
 		}
 		startTS := txn.StartTS()
-		err = RemoveBackfillJob(sess, true, bJobs[0])
+		err = RemoveBackfillJob(se, true, bJobs[0])
 		if err == nil {
 			for _, bj := range bJobs {
 				bj.State = model.JobStateCancelled
 				bj.FinishTS = startTS
 			}
-			err = AddBackfillHistoryJob(sess, bJobs)
+			err = AddBackfillHistoryJob(se, bJobs)
 		}
 		logutil.BgLogger().Info("[ddl] move backfill jobs to history table", zap.Int("job count", len(bJobs)))
 		return errors.Trace(err)

ddl/column.go

@@ -806,7 +806,13 @@ func doReorgWorkForModifyColumnMultiSchema(w *worker, d *ddlCtx, t *meta.Meta, j
 func doReorgWorkForModifyColumn(w *worker, d *ddlCtx, t *meta.Meta, job *model.Job, tbl table.Table,
 	oldCol, changingCol *model.ColumnInfo, changingIdxs []*model.IndexInfo) (done bool, ver int64, err error) {
 	job.ReorgMeta.ReorgTp = model.ReorgTypeTxn
-	rh := newReorgHandler(t, w.sess)
+	sctx, err1 := w.sessPool.get()
+	if err1 != nil {
+		err = errors.Trace(err1)
+		return
+	}
+	defer w.sessPool.put(sctx)
+	rh := newReorgHandler(newSession(sctx))
 	dbInfo, err := t.GetDatabase(job.SchemaID)
 	if err != nil {
 		return false, ver, errors.Trace(err)
@@ -1291,8 +1297,8 @@ func (w *updateColumnWorker) getRowRecord(handle kv.Handle, recordKey []byte, ra
 	if err != nil {
 		return w.reformatErrors(err)
 	}
-	if w.sessCtx.GetSessionVars().StmtCtx.GetWarnings() != nil && len(w.sessCtx.GetSessionVars().StmtCtx.GetWarnings()) != 0 {
-		warn := w.sessCtx.GetSessionVars().StmtCtx.GetWarnings()
+	warn := w.sessCtx.GetSessionVars().StmtCtx.GetWarnings()
+	if len(warn) != 0 {
 		//nolint:forcetypeassert
 		recordWarning = errors.Cause(w.reformatErrors(warn[0].Err)).(*terror.Error)
 	}
@@ -1376,8 +1382,9 @@ func (w *updateColumnWorker) BackfillDataInTxn(handleRange reorgBackfillTask) (t
 		taskCtx.nextKey = nextKey
 		taskCtx.done = taskDone
 
-		warningsMap := make(map[errors.ErrorID]*terror.Error, len(rowRecords))
-		warningsCountMap := make(map[errors.ErrorID]int64, len(rowRecords))
+		// Optimize for few warnings!
+		warningsMap := make(map[errors.ErrorID]*terror.Error, 2)
+		warningsCountMap := make(map[errors.ErrorID]int64, 2)
 		for _, rowRecord := range rowRecords {
 			taskCtx.scanCount++
 

ddl/column_type_change_test.go

@@ -2421,3 +2421,18 @@ func TestColumnTypeChangeTimestampToInt(t *testing.T) {
 	tk.MustExec("alter table t add index idx1(id, c1);")
 	tk.MustExec("admin check table t")
 }
+
+func TestFixDDLTxnWillConflictWithReorgTxn(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+
+	tk.MustExec("create table t (a int)")
+	tk.MustExec("set global tidb_ddl_enable_fast_reorg = OFF")
+	tk.MustExec("alter table t add index(a)")
+	tk.MustExec("set @@sql_mode=''")
+	tk.MustExec("insert into t values(128),(129)")
+	tk.MustExec("alter table t modify column a tinyint")
+
+	tk.MustQuery("show warnings").Check(testkit.Rows("Warning 1690 2 warnings with this error code, first warning: constant 128 overflows tinyint"))
+}

ddl/db_partition_test.go

@@ -4528,6 +4528,25 @@ func TestPartitionTableWithAnsiQuotes(t *testing.T) {
 		` PARTITION "pMax" VALUES LESS THAN (MAXVALUE,MAXVALUE))`))
 }
 
+func TestAlterModifyPartitionColTruncateWarning(t *testing.T) {
+	t.Skip("waiting for supporting Modify Partition Column again")
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	schemaName := "truncWarn"
+	tk.MustExec("create database " + schemaName)
+	tk.MustExec("use " + schemaName)
+	tk.MustExec(`set sql_mode = default`)
+	tk.MustExec(`create table t (a varchar(255)) partition by range columns (a) (partition p1 values less than ("0"), partition p2 values less than ("zzzz"))`)
+	tk.MustExec(`insert into t values ("123456"),(" 654321")`)
+	tk.MustContainErrMsg(`alter table t modify a varchar(5)`, "[types:1265]Data truncated for column 'a', value is '")
+	tk.MustExec(`set sql_mode = ''`)
+	tk.MustExec(`alter table t modify a varchar(5)`)
+	// Fix the duplicate warning, see https://github.com/pingcap/tidb/issues/38699
+	tk.MustQuery(`show warnings`).Check(testkit.Rows(""+
+		"Warning 1265 Data truncated for column 'a', value is ' 654321'",
+		"Warning 1265 Data truncated for column 'a', value is ' 654321'"))
+}
+
 func TestAlterModifyColumnOnPartitionedTableRename(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)

ddl/db_test.go

@@ -618,10 +618,7 @@ func TestAddExpressionIndexRollback(t *testing.T) {
 	// Check whether the reorg information is cleaned up.
 	err := sessiontxn.NewTxn(context.Background(), ctx)
 	require.NoError(t, err)
-	txn, err := ctx.Txn(true)
-	require.NoError(t, err)
-	m := meta.NewMeta(txn)
-	element, start, end, physicalID, err := ddl.NewReorgHandlerForTest(m, testkit.NewTestKit(t, store).Session()).GetDDLReorgHandle(currJob)
+	element, start, end, physicalID, err := ddl.NewReorgHandlerForTest(testkit.NewTestKit(t, store).Session()).GetDDLReorgHandle(currJob)
 	require.True(t, meta.ErrDDLReorgElementNotExist.Equal(err))
 	require.Nil(t, element)
 	require.Nil(t, start)

ddl/ddl.go

@@ -1343,7 +1343,7 @@ func GetDDLInfo(s sessionctx.Context) (*Info, error) {
 		return info, nil
 	}
 
-	_, info.ReorgHandle, _, _, err = newReorgHandler(t, sess).GetDDLReorgHandle(reorgJob)
+	_, info.ReorgHandle, _, _, err = newReorgHandler(sess).GetDDLReorgHandle(reorgJob)
 	if err != nil {
 		if meta.ErrDDLReorgElementNotExist.Equal(err) {
 			return info, nil
@@ -1584,6 +1584,19 @@ func (s *session) session() sessionctx.Context {
 	return s.Context
 }
 
+func (s *session) runInTxn(f func(*session) error) (err error) {
+	err = s.begin()
+	if err != nil {
+		return err
+	}
+	err = f(s)
+	if err != nil {
+		s.rollback()
+		return
+	}
+	return errors.Trace(s.commit())
+}
+
 // GetAllHistoryDDLJobs get all the done DDL jobs.
 func GetAllHistoryDDLJobs(m *meta.Meta) ([]*model.Job, error) {
 	iterator, err := GetLastHistoryDDLJobsIterator(m)

ddl/ddl_worker.go

@@ -699,6 +699,7 @@ func (w *worker) HandleJobDone(d *ddlCtx, job *model.Job, t *meta.Meta) error {
 	if err != nil {
 		return err
 	}
+	CleanupDDLReorgHandles(job, w.sess)
 	asyncNotify(d.ddlJobDoneCh)
 	return nil
 }

ddl/index.go

@@ -882,7 +882,13 @@ func doReorgWorkForCreateIndex(w *worker, d *ddlCtx, t *meta.Meta, job *model.Jo
 func runReorgJobAndHandleErr(w *worker, d *ddlCtx, t *meta.Meta, job *model.Job,
 	tbl table.Table, indexInfo *model.IndexInfo, mergingTmpIdx bool) (done bool, ver int64, err error) {
 	elements := []*meta.Element{{ID: indexInfo.ID, TypeKey: meta.IndexElementKey}}
-	rh := newReorgHandler(t, w.sess)
+	sctx, err1 := w.sessPool.get()
+	if err1 != nil {
+		err = err1
+		return
+	}
+	defer w.sessPool.put(sctx)
+	rh := newReorgHandler(newSession(sctx))
 	dbInfo, err := t.GetDatabase(job.SchemaID)
 	if err != nil {
 		return false, ver, errors.Trace(err)
@@ -1274,13 +1280,10 @@ func (w *baseIndexWorker) String() string {
 }
 
 func (w *baseIndexWorker) UpdateTask(bfJob *BackfillJob) error {
-	sess, ok := w.backfillCtx.sessCtx.(*session)
-	if !ok {
-		return errors.Errorf("sess ctx:%#v convert session failed", w.backfillCtx.sessCtx)
-	}
+	s := newSession(w.backfillCtx.sessCtx)
 
-	return runInTxn(sess, func(se *session) error {
-		jobs, err := GetBackfillJobs(sess, BackfillTable, fmt.Sprintf("ddl_job_id = %d and ele_id = %d and ele_key = '%s' and id = %d",
+	return s.runInTxn(func(se *session) error {
+		jobs, err := GetBackfillJobs(se, BackfillTable, fmt.Sprintf("ddl_job_id = %d and ele_id = %d and ele_key = '%s' and id = %d",
 			bfJob.JobID, bfJob.EleID, bfJob.EleKey, bfJob.ID), "update_backfill_task")
 		if err != nil {
 			return err
@@ -1297,26 +1300,23 @@ func (w *baseIndexWorker) UpdateTask(bfJob *BackfillJob) error {
 			return err
 		}
 		bfJob.InstanceLease = GetLeaseGoTime(currTime, InstanceLease)
-		return updateBackfillJob(sess, BackfillTable, bfJob, "update_backfill_task")
+		return updateBackfillJob(se, BackfillTable, bfJob, "update_backfill_task")
 	})
 }
 
 func (w *baseIndexWorker) FinishTask(bfJob *BackfillJob) error {
-	sess, ok := w.backfillCtx.sessCtx.(*session)
-	if !ok {
-		return errors.Errorf("sess ctx:%#v convert session failed", w.backfillCtx.sessCtx)
-	}
-	return runInTxn(sess, func(se *session) error {
+	s := newSession(w.backfillCtx.sessCtx)
+	return s.runInTxn(func(se *session) error {
 		txn, err := se.txn()
 		if err != nil {
 			return errors.Trace(err)
 		}
 		bfJob.FinishTS = txn.StartTS()
-		err = RemoveBackfillJob(sess, false, bfJob)
+		err = RemoveBackfillJob(se, false, bfJob)
 		if err != nil {
 			return err
 		}
-		return AddBackfillHistoryJob(sess, []*BackfillJob{bfJob})
+		return AddBackfillHistoryJob(se, []*BackfillJob{bfJob})
 	})
 }