move-tables: ensure target tables are dropped in noop mode

go/logic/migrator.go

@@ -3218,13 +3218,18 @@ func (mgtr *Migrator) moveTablesFinalCleanup() error {
 	targetDatabaseName := mgtr.migrationContext.GetTargetDatabaseName()
 	checkpointTableName := mgtr.migrationContext.GetCheckpointTableName()
 
-	if mgtr.migrationContext.OkToDropTable {
-		// The source `__del` rollback handle only exists after a real cutover,
-		// never in Noop runs. It must be dropped on the source primary: the
-		// inspector/streamer source connections may point at a read replica, so the
-		// drop goes through the dedicated source-primary handle.
-		if !mgtr.migrationContext.Noop {
-			if err := mgtr.retryOperation(mgtr.dropMoveTablesSourceOldTables); err != nil {
+	// A resumed noop reuses the target tables and checkpoint from the interrupted
+	// migration, so it must preserve both. A fresh noop creates target tables and
+	// a checkpoint only for schema validation, so it must remove those artifacts
+	// regardless of --ok-to-drop-table.
+	if mgtr.migrationContext.Noop {
+		if mgtr.migrationContext.Resume {
+			return nil
+		}
+		for _, mt := range mgtr.migrationContext.OrderedMoveTables() {
+			if err := mgtr.retryOperation(func() error {
+				return mgtr.applier.dropTable(mt.TargetTableName)
+			}); err != nil {
 				return err
 			}
 		}
@@ -3236,7 +3241,19 @@ func (mgtr *Migrator) moveTablesFinalCleanup() error {
 		return nil
 	}
 
-	if mgtr.migrationContext.Noop {
+	if mgtr.migrationContext.OkToDropTable {
+		// The source `__del` rollback handle only exists after a real cutover,
+		// never in Noop runs. It must be dropped on the source primary: the
+		// inspector/streamer source connections may point at a read replica, so the
+		// drop goes through the dedicated source-primary handle.
+		if err := mgtr.retryOperation(mgtr.dropMoveTablesSourceOldTables); err != nil {
+			return err
+		}
+		if mgtr.migrationContext.Checkpoint {
+			if err := mgtr.retryOperation(mgtr.applier.DropCheckpointTable); err != nil {
+				return err
+			}
+		}
 		return nil
 	}
 

go/logic/migrator_test.go

@@ -622,6 +622,82 @@ func (suite *MigratorTestSuite) TestMoveTablesStateInitializesColumnMetadata() {
 	})
 }
 
+func (suite *MigratorTestSuite) TestMoveTablesNoopDropsTargetTables() {
+	ctx := context.Background()
+	targetTableNames := []string{testMysqlTableName, "test_noop_target"}
+
+	migrationContext := newTestMigrationContext()
+	migrationContext.Noop = true
+	migrationContext.Checkpoint = true
+	migrationContext.MoveTables.TableNames = targetTableNames
+	migrationContext.MoveTables.TargetDatabase = testMysqlDatabase
+	migrationContext.InitMoveTableContainers()
+
+	migrator := NewMigrator(migrationContext, "test")
+	migrator.applier = NewApplier(migrationContext)
+	migrator.applier.moveTablesTargetDB = suite.db
+	suite.Require().NoError(migrator.applier.CreateCheckpointTable())
+
+	for _, tableName := range targetTableNames {
+		_, err := suite.db.ExecContext(ctx, fmt.Sprintf("CREATE TABLE %s.%s (id INT PRIMARY KEY)",
+			sql.EscapeName(testMysqlDatabase), sql.EscapeName(tableName)))
+		suite.Require().NoError(err)
+	}
+
+	suite.Require().NoError(migrator.moveTablesFinalCleanup())
+
+	for _, tableName := range targetTableNames {
+		exists, err := migrator.applier.targetTableExists(tableName)
+		suite.Require().NoError(err)
+		suite.Require().False(exists, "noop cleanup must drop target table %s", tableName)
+	}
+	checkpointExists, err := migrator.applier.targetTableExists(migrationContext.GetCheckpointTableName())
+	suite.Require().NoError(err)
+	suite.Require().False(checkpointExists, "fresh noop cleanup must drop its checkpoint table")
+}
+
+func (suite *MigratorTestSuite) TestMoveTablesResumedNoopPreservesTargetTables() {
+	ctx := context.Background()
+	targetTableNames := []string{testMysqlTableName, "test_noop_resume_target"}
+
+	migrationContext := newTestMigrationContext()
+	migrationContext.Noop = true
+	migrationContext.Resume = true
+	migrationContext.Checkpoint = true
+	migrationContext.MoveTables.TableNames = targetTableNames
+	migrationContext.MoveTables.TargetDatabase = testMysqlDatabase
+	migrationContext.InitMoveTableContainers()
+
+	migrator := NewMigrator(migrationContext, "test")
+	migrator.applier = NewApplier(migrationContext)
+	migrator.applier.moveTablesTargetDB = suite.db
+	suite.Require().NoError(migrator.applier.CreateCheckpointTable())
+
+	for _, tableName := range targetTableNames {
+		_, err := suite.db.ExecContext(ctx, fmt.Sprintf("CREATE TABLE %s.%s (id INT PRIMARY KEY)",
+			sql.EscapeName(testMysqlDatabase), sql.EscapeName(tableName)))
+		suite.Require().NoError(err)
+	}
+	defer func() {
+		for _, tableName := range append(targetTableNames, migrationContext.GetCheckpointTableName()) {
+			_, err := suite.db.ExecContext(ctx, fmt.Sprintf("DROP TABLE IF EXISTS %s.%s",
+				sql.EscapeName(testMysqlDatabase), sql.EscapeName(tableName)))
+			suite.Require().NoError(err)
+		}
+	}()
+
+	suite.Require().NoError(migrator.moveTablesFinalCleanup())
+
+	for _, tableName := range targetTableNames {
+		exists, err := migrator.applier.targetTableExists(tableName)
+		suite.Require().NoError(err)
+		suite.Require().True(exists, "resumed noop cleanup must preserve target table %s", tableName)
+	}
+	checkpointExists, err := migrator.applier.targetTableExists(migrationContext.GetCheckpointTableName())
+	suite.Require().NoError(err)
+	suite.Require().True(checkpointExists, "resumed noop cleanup must preserve its checkpoint table")
+}
+
 func (suite *MigratorTestSuite) TestRetryBatchCopyWithHooks() {
 	ctx := context.Background()