ddl: fix add index's merge with multi-schema optimization (#51747)

close #51746

pkg/ddl/index_merge_tmp.go

@@ -35,10 +35,9 @@ import (
 
 func (w *mergeIndexWorker) batchCheckTemporaryUniqueKey(
 	txn kv.Transaction,
-	idxInfo *model.IndexInfo,
 	idxRecords []*temporaryIndexRecord,
 ) error {
-	if !idxInfo.Unique {
+	if !w.currentIndex.Unique {
 		// non-unique key need no check, just overwrite it,
 		// because in most case, backfilling indices is not exists.
 		return nil
@@ -55,7 +54,7 @@ func (w *mergeIndexWorker) batchCheckTemporaryUniqueKey(
 			err := checkTempIndexKey(txn, idxRecords[i], val, w.table)
 			if err != nil {
 				if kv.ErrKeyExists.Equal(err) {
-					return driver.ExtractKeyExistsErrFromIndex(key, val, w.table.Meta(), idxInfo.ID)
+					return driver.ExtractKeyExistsErrFromIndex(key, val, w.table.Meta(), w.currentIndex.ID)
 				}
 				return errors.Trace(err)
 			}
@@ -128,6 +127,10 @@ type mergeIndexWorker struct {
 	tmpIdxRecords []*temporaryIndexRecord
 	originIdxKeys []kv.Key
 	tmpIdxKeys    []kv.Key
+
+	needValidateKey        bool
+	currentTempIndexPrefix []byte
+	currentIndex           *model.IndexInfo
 }
 
 func newMergeTempIndexWorker(bfCtx *backfillCtx, t table.PhysicalTable, elements []*meta.Element) *mergeIndexWorker {
@@ -144,68 +147,99 @@ func newMergeTempIndexWorker(bfCtx *backfillCtx, t table.PhysicalTable, elements
 	}
 }
 
+func (w *mergeIndexWorker) validateTaskRange(taskRange *reorgBackfillTask) (skip bool, err error) {
+	tmpID, err := tablecodec.DecodeIndexID(taskRange.startKey)
+	if err != nil {
+		return false, err
+	}
+	startIndexID := tmpID & tablecodec.IndexIDMask
+	tmpID, err = tablecodec.DecodeIndexID(taskRange.endKey)
+	if err != nil {
+		return false, err
+	}
+	endIndexID := tmpID & tablecodec.IndexIDMask
+
+	w.needValidateKey = startIndexID != endIndexID
+	containsTargetID := false
+	for _, idx := range w.indexes {
+		idxInfo := idx.Meta()
+		if idxInfo.ID == startIndexID {
+			containsTargetID = true
+			w.currentIndex = idxInfo
+			break
+		}
+		if idxInfo.ID == endIndexID {
+			containsTargetID = true
+		}
+	}
+	return !containsTargetID, nil
+}
+
 // BackfillData merge temp index data in txn.
 func (w *mergeIndexWorker) BackfillData(taskRange reorgBackfillTask) (taskCtx backfillTaskContext, errInTxn error) {
+	skip, err := w.validateTaskRange(&taskRange)
+	if skip || err != nil {
+		return taskCtx, err
+	}
+
 	oprStartTime := time.Now()
 	ctx := kv.WithInternalSourceAndTaskType(context.Background(), w.jobContext.ddlJobSourceType(), kvutil.ExplicitTypeDDL)
-	for _, idx := range w.indexes {
-		idx := idx // Make linter noloopclosure happy.
-		errInTxn = kv.RunInNewTxn(ctx, w.sessCtx.GetStore(), true, func(_ context.Context, txn kv.Transaction) error {
-			taskCtx.addedCount = 0
-			taskCtx.scanCount = 0
-			updateTxnEntrySizeLimitIfNeeded(txn)
-			txn.SetOption(kv.Priority, taskRange.priority)
-			if tagger := w.GetCtx().getResourceGroupTaggerForTopSQL(taskRange.getJobID()); tagger != nil {
-				txn.SetOption(kv.ResourceGroupTagger, tagger)
-			}
-			txn.SetOption(kv.ResourceGroupName, w.jobContext.resourceGroupName)
 
-			tmpIdxRecords, nextKey, taskDone, err := w.fetchTempIndexVals(txn, idx.Meta(), taskRange)
-			if err != nil {
-				return errors.Trace(err)
+	errInTxn = kv.RunInNewTxn(ctx, w.sessCtx.GetStore(), true, func(_ context.Context, txn kv.Transaction) error {
+		taskCtx.addedCount = 0
+		taskCtx.scanCount = 0
+		updateTxnEntrySizeLimitIfNeeded(txn)
+		txn.SetOption(kv.Priority, taskRange.priority)
+		if tagger := w.GetCtx().getResourceGroupTaggerForTopSQL(taskRange.getJobID()); tagger != nil {
+			txn.SetOption(kv.ResourceGroupTagger, tagger)
+		}
+		txn.SetOption(kv.ResourceGroupName, w.jobContext.resourceGroupName)
+
+		tmpIdxRecords, nextKey, taskDone, err := w.fetchTempIndexVals(txn, taskRange)
+		if err != nil {
+			return errors.Trace(err)
+		}
+		taskCtx.nextKey = nextKey
+		taskCtx.done = taskDone
+
+		err = w.batchCheckTemporaryUniqueKey(txn, tmpIdxRecords)
+		if err != nil {
+			return errors.Trace(err)
+		}
+
+		for i, idxRecord := range tmpIdxRecords {
+			taskCtx.scanCount++
+			// The index is already exists, we skip it, no needs to backfill it.
+			// The following update, delete, insert on these rows, TiDB can handle it correctly.
+			// If all batch are skipped, update first index key to make txn commit to release lock.
+			if idxRecord.skip {
+				continue
 			}
-			taskCtx.nextKey = nextKey
-			taskCtx.done = taskDone
 
-			err = w.batchCheckTemporaryUniqueKey(txn, idx.Meta(), tmpIdxRecords)
+			// Lock the corresponding row keys so that it doesn't modify the index KVs
+			// that are changing by a pessimistic transaction.
+			rowKey := tablecodec.EncodeRecordKey(w.table.RecordPrefix(), idxRecord.handle)
+			err := txn.LockKeys(context.Background(), new(kv.LockCtx), rowKey)
 			if err != nil {
 				return errors.Trace(err)
 			}
 
-			for i, idxRecord := range tmpIdxRecords {
-				taskCtx.scanCount++
-				// The index is already exists, we skip it, no needs to backfill it.
-				// The following update, delete, insert on these rows, TiDB can handle it correctly.
-				// If all batch are skipped, update first index key to make txn commit to release lock.
-				if idxRecord.skip {
-					continue
-				}
-
-				// Lock the corresponding row keys so that it doesn't modify the index KVs
-				// that are changing by a pessimistic transaction.
-				rowKey := tablecodec.EncodeRecordKey(w.table.RecordPrefix(), idxRecord.handle)
-				err := txn.LockKeys(context.Background(), new(kv.LockCtx), rowKey)
-				if err != nil {
-					return errors.Trace(err)
-				}
-
-				if idxRecord.delete {
-					if idxRecord.unique {
-						err = txn.GetMemBuffer().DeleteWithFlags(w.originIdxKeys[i], kv.SetNeedLocked)
-					} else {
-						err = txn.GetMemBuffer().Delete(w.originIdxKeys[i])
-					}
+			if idxRecord.delete {
+				if idxRecord.unique {
+					err = txn.GetMemBuffer().DeleteWithFlags(w.originIdxKeys[i], kv.SetNeedLocked)
 				} else {
-					err = txn.GetMemBuffer().Set(w.originIdxKeys[i], idxRecord.vals)
-				}
-				if err != nil {
-					return err
+					err = txn.GetMemBuffer().Delete(w.originIdxKeys[i])
 				}
-				taskCtx.addedCount++
+			} else {
+				err = txn.GetMemBuffer().Set(w.originIdxKeys[i], idxRecord.vals)
 			}
-			return nil
-		})
-	}
+			if err != nil {
+				return err
+			}
+			taskCtx.addedCount++
+		}
+		return nil
+	})
 
 	failpoint.Inject("mockDMLExecutionMerging", func(val failpoint.Value) {
 		//nolint:forcetypeassert
@@ -228,9 +262,41 @@ func (w *mergeIndexWorker) GetCtx() *backfillCtx {
 	return w.backfillCtx
 }
 
+func (w *mergeIndexWorker) prefixIsChanged(newKey kv.Key) bool {
+	return len(w.currentTempIndexPrefix) == 0 || !bytes.HasPrefix(newKey, w.currentTempIndexPrefix)
+}
+
+func (w *mergeIndexWorker) updateCurrentIndexInfo(newIndexKey kv.Key) (skip bool, err error) {
+	tempIdxID, err := tablecodec.DecodeIndexID(newIndexKey)
+	if err != nil {
+		return false, err
+	}
+	idxID := tablecodec.IndexIDMask & tempIdxID
+	var curIdx *model.IndexInfo
+	for _, idx := range w.indexes {
+		if idx.Meta().ID == idxID {
+			curIdx = idx.Meta()
+		}
+	}
+	if curIdx == nil {
+		// Index IDs are always increasing, but not always continuous:
+		// if DDL adds another index between these indexes, it is possible that:
+		//   multi-schema add index IDs = [1, 2, 4, 5]
+		//   another index ID = [3]
+		// If the new index get rollback, temp index 0xFFxxx03 may have dirty records.
+		// We should skip these dirty records.
+		return true, nil
+	}
+	pfx := tablecodec.CutIndexPrefix(newIndexKey)
+
+	w.currentTempIndexPrefix = kv.Key(pfx).Clone()
+	w.currentIndex = curIdx
+
+	return false, nil
+}
+
 func (w *mergeIndexWorker) fetchTempIndexVals(
 	txn kv.Transaction,
-	indexInfo *model.IndexInfo,
 	taskRange reorgBackfillTask,
 ) ([]*temporaryIndexRecord, kv.Key, bool, error) {
 	startTime := time.Now()
@@ -254,11 +320,18 @@ func (w *mergeIndexWorker) fetchTempIndexVals(
 				return false, nil
 			}
 
+			if w.needValidateKey && w.prefixIsChanged(indexKey) {
+				skip, err := w.updateCurrentIndexInfo(indexKey)
+				if err != nil || skip {
+					return skip, err
+				}
+			}
+
 			tempIdxVal, err := tablecodec.DecodeTempIndexValue(rawValue)
 			if err != nil {
 				return false, err
 			}
-			tempIdxVal, err = decodeTempIndexHandleFromIndexKV(indexKey, tempIdxVal, len(indexInfo.Columns))
+			tempIdxVal, err = decodeTempIndexHandleFromIndexKV(indexKey, tempIdxVal, len(w.currentIndex.Columns))
 			if err != nil {
 				return false, err
 			}

pkg/ddl/ingest/BUILD.bazel

@@ -68,7 +68,7 @@ go_test(
     embed = [":ingest"],
     flaky = True,
     race = "on",
-    shard_count = 16,
+    shard_count = 17,
     deps = [
         "//pkg/config",
         "//pkg/ddl",

pkg/ddl/ingest/integration_test.go

@@ -340,3 +340,30 @@ func TestAddIndexDuplicateMessage(t *testing.T) {
 	tk.MustExec("admin check table t;")
 	tk.MustQuery("select * from t;").Check(testkit.Rows("1 1 1", "2 1 2"))
 }
+
+func TestMultiSchemaAddIndexMerge(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	defer ingesttestutil.InjectMockBackendMgr(t, store)()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk2 := testkit.NewTestKit(t, store)
+	tk2.MustExec("use test")
+
+	tk.MustExec("create table t (a int, b int);")
+	tk.MustExec("insert into t values (1, 1), (2, 2), (3, 3);")
+
+	first := true
+	var tk2Err error
+	ingest.MockExecAfterWriteRow = func() {
+		if !first {
+			return
+		}
+		_, tk2Err = tk2.Exec("insert into t values (4, 4);")
+		first = false
+	}
+
+	tk.MustExec("alter table t add index idx1(a), add index idx2(b);")
+	require.False(t, first)
+	require.NoError(t, tk2Err)
+	tk.MustExec("admin check table t;")
+}

pkg/ddl/reorg.go

@@ -706,7 +706,10 @@ func getReorgInfo(ctx *JobContext, d *ddlCtx, rh *reorgHandler, job *model.Job,
 			tb = tbl.(table.PhysicalTable)
 		}
 		if mergingTmpIdx {
-			start, end = tablecodec.GetTableIndexKeyRange(pid, tablecodec.TempIndexPrefix|elements[0].ID)
+			firstElemTempID := tablecodec.TempIndexPrefix | elements[0].ID
+			lastElemTempID := tablecodec.TempIndexPrefix | elements[len(elements)-1].ID
+			start = tablecodec.EncodeIndexSeekKey(pid, firstElemTempID, nil)
+			end = tablecodec.EncodeIndexSeekKey(pid, lastElemTempID, []byte{255})
 		} else {
 			start, end, err = getTableRange(ctx, d, tb, ver.Ver, job.Priority)
 			if err != nil {