Function findRollbacks

scripts/develop/dbrecovery.go:234–257

findRollbacks returns tracked migrations whose file no longer exists on disk, sorted in descending version order.

(ctx context.Context, db *sql.DB, migrDir string)

// findRollbacks returns tracked migrations whose file no longer
// exists on disk, sorted in descending version order.
func findRollbacks(ctx context.Context, db *sql.DB, migrDir string) ([]rollbackEntry, error) {
	rows, err := db.QueryContext(ctx, `
		SELECT version, filename, down_sql
		FROM _develop.applied_migrations
		ORDER BY version DESC
	`)
	if err != nil {
		return nil, xerrors.Errorf("query tracking table: %w", err)
	}
	defer rows.Close()

	var rollbacks []rollbackEntry
	for rows.Next() {
		var rb rollbackEntry
		if err := rows.Scan(&rb.version, &rb.filename, &rb.downSQL); err != nil {
			return nil, xerrors.Errorf("scan row: %w", err)
		}
		downPath := filepath.Join(migrDir, rb.filename)
		if _, err := os.Stat(downPath); err != nil {
			rollbacks = append(rollbacks, rb)
		}
	}
	return rollbacks, rows.Err()
}

// findContentChanges compares tracked up/down SQL against disk
// for all tracked versions whose files still exist.