code: func NewPostgresDataStore(routeType string, pgx *pgx.ConnPool) *pgDataStore {
  	tableName := ""
  	switch routeType {
  	case routeTypeHTTP:
  		tableName = tableNameHTTP
  	case routeTypeTCP:
  		tableName = tableNameTCP
  	default:
  		panic(fmt.Sprintf("unknown routeType: %q", routeType))
  	}
  	return &pgDataStore{
  		pgx:       pgx,
  		routeType: routeType,
  		tableName: tableName,
  	}
  }
docs: // NewPostgresDataStore returns a DataStore that stores route information in a
  // Postgres database. It uses pg_notify and a listener connection to watch for
  // route changes.