Remove BeforeBackfill hook (#312)

Remove the `BeforeBackfill` hook.

The `BeforeBackfill` hook was added along with the `BeforeStartDDL` and
`AfterStartDDL` hooks in #290, but is of limited use as a hook that runs
only after successful execution of start phase DDL. Prefer a simpler API
with fewer hooks until there is a demonstrated need for it.

pkg/roll/execute.go

@@ -20,12 +20,6 @@ func (m *Roll) Start(ctx context.Context, migration *migrations.Migration, cbs .
 		return err
 	}
 
-	if m.migrationHooks.BeforeBackfill != nil {
-		if err := m.migrationHooks.BeforeBackfill(m); err != nil {
-			return fmt.Errorf("failed to execute BeforeBackfill hook: %w", err)
-		}
-	}
-
 	// perform backfills for the tables that require it
 	return m.performBackfills(ctx, tablesToBackfill)
 }

pkg/roll/execute_test.go

@@ -478,15 +478,11 @@ func TestMigrationHooksAreInvoked(t *testing.T) {
 
 	options := []roll.Option{roll.WithMigrationHooks(roll.MigrationHooks{
 		BeforeStartDDL: func(m *roll.Roll) error {
-			_, err := m.PgConn().ExecContext(context.Background(), "CREATE TABLE IF NOT EXISTS before_start_ddl (id integer)")
+			_, err := m.PgConn().ExecContext(context.Background(), "CREATE TABLE before_start_ddl (id integer)")
 			return err
 		},
 		AfterStartDDL: func(m *roll.Roll) error {
-			_, err := m.PgConn().ExecContext(context.Background(), "CREATE TABLE IF NOT EXISTS after_start_ddl (id integer)")
-			return err
-		},
-		BeforeBackfill: func(m *roll.Roll) error {
-			_, err := m.PgConn().ExecContext(context.Background(), "CREATE TABLE IF NOT EXISTS before_backfill (id integer)")
+			_, err := m.PgConn().ExecContext(context.Background(), "CREATE TABLE after_start_ddl (id integer)")
 			return err
 		},
 	})}
@@ -508,30 +504,6 @@ func TestMigrationHooksAreInvoked(t *testing.T) {
 		// Complete the migration
 		err = mig.Complete(ctx)
 		assert.NoError(t, err)
-
-		// Insert some data into the table created by the migration
-		_, err = db.ExecContext(ctx, "INSERT INTO table1 (id, name) VALUES (1, 'alice')")
-		assert.NoError(t, err)
-
-		// Start a migration that requires a backfill
-		err = mig.Start(ctx, &migrations.Migration{
-			Name: "02_add_column",
-			Operations: migrations.Operations{
-				&migrations.OpAddColumn{
-					Table: "table1",
-					Column: migrations.Column{
-						Name:     "description",
-						Type:     "text",
-						Nullable: ptr(false),
-					},
-					Up: ptr("'this is a description'"),
-				},
-			},
-		})
-		assert.NoError(t, err)
-
-		// ensure that the before_backfill table was created
-		assert.True(t, tableExists(t, db, "public", "before_backfill"))
 	})
 }
 

pkg/roll/options.go

@@ -21,8 +21,6 @@ type MigrationHooks struct {
 	BeforeStartDDL func(*Roll) error
 	// AfterStartDDL is called after the DDL phase of migration start is complete
 	AfterStartDDL func(*Roll) error
-	// BeforeBackfill is called before the backfill phase of migration start
-	BeforeBackfill func(*Roll) error
 }
 
 type Option func(*options)