infoschema_v2: fix rename table

pkg/infoschema/builder.go

@@ -385,19 +385,18 @@ func dropTableForUpdate(b *Builder, newTableID, oldTableID int64, dbInfo *model.
 			// TODO: Check how this would work with ADD/REMOVE Partitioning,
 			// which may have AutoID not connected to tableID
 			// TODO: can there be _tidb_rowid AutoID per partition?
-			oldAllocs, _ := allocByID(b.infoSchema, oldTableID)
+			oldAllocs, _ := allocByID(b, oldTableID)
 			newAllocs = filterAllocators(diff, oldAllocs)
 		}
 
 		tmpIDs := tblIDs
 		if (diff.Type == model.ActionRenameTable || diff.Type == model.ActionRenameTables) && diff.OldSchemaID != diff.SchemaID {
-			oldRoDBInfo, ok := b.infoSchema.SchemaByID(diff.OldSchemaID)
+			oldDBInfo, ok := oldSchemaInfo(b, diff)
 			if !ok {
 				return nil, newAllocs, ErrDatabaseNotExists.GenWithStackByArgs(
 					fmt.Sprintf("(Schema ID %d)", diff.OldSchemaID),
 				)
 			}
-			oldDBInfo := b.getSchemaAndCopyIfNecessary(oldRoDBInfo.Name.L)
 			tmpIDs = applyDropTable(b, diff, oldDBInfo, oldTableID, tmpIDs)
 		} else {
 			tmpIDs = applyDropTable(b, diff, dbInfo, oldTableID, tmpIDs)

pkg/infoschema/infoschema.go

@@ -279,15 +279,6 @@ func (is *infoSchema) SchemaTableInfos(schema model.CIStr) []*model.TableInfo {
 	return getTableInfoList(is.SchemaTables(schema))
 }
 
-// allocByID returns the Allocators of a table.
-func allocByID(is InfoSchema, id int64) (autoid.Allocators, bool) {
-	tbl, ok := is.TableByID(id)
-	if !ok {
-		return autoid.Allocators{}, false
-	}
-	return tbl.Allocators(nil), true
-}
-
 // AllSchemaNames returns all the schemas' names.
 func AllSchemaNames(is InfoSchema) (names []string) {
 	schemas := is.AllSchemaNames()

pkg/infoschema/infoschema_v2.go

@@ -685,6 +685,33 @@ func updateInfoSchemaBundles(b *Builder) {
 	}
 }
 
+func oldSchemaInfo(b *Builder, diff *model.SchemaDiff) (*model.DBInfo, bool) {
+	if b.enableV2 {
+		return b.infoschemaV2.SchemaByID(diff.OldSchemaID)
+	}
+
+	oldRoDBInfo, ok := b.infoSchema.SchemaByID(diff.OldSchemaID)
+	if ok {
+		oldRoDBInfo = b.getSchemaAndCopyIfNecessary(oldRoDBInfo.Name.L)
+	}
+	return oldRoDBInfo, ok
+}
+
+// allocByID returns the Allocators of a table.
+func allocByID(b *Builder, id int64) (autoid.Allocators, bool) {
+	var is InfoSchema
+	if b.enableV2 {
+		is = &b.infoschemaV2
+	} else {
+		is = b.infoSchema
+	}
+	tbl, ok := is.TableByID(id)
+	if !ok {
+		return autoid.Allocators{}, false
+	}
+	return tbl.Allocators(nil), true
+}
+
 // TODO: more UT to check the correctness.
 func (b *Builder) applyTableUpdateV2(m *meta.Meta, diff *model.SchemaDiff) ([]int64, error) {
 	oldDBInfo, ok := b.infoschemaV2.SchemaByID(diff.SchemaID)