Future<PostgreSQLConnection> getDatabaseConnection()

Retrieves a connection to the database this instance connects to.

If no connection exists, one will be created. A store will have no more than one connection at a time. You should rarely need to access this connection directly.

Source 

Future<PostgreSQLConnection> getDatabaseConnection() async {
  if (_databaseConnection == null || _databaseConnection.isClosed) {
    if (connectFunction == null) {
      throw new QueryException(QueryExceptionEvent.internalFailure,
          message: "Could not connect to database, no connect function.");
    }

    if (_pendingConnectionCompleter == null) {
      _pendingConnectionCompleter = new Completer<PostgreSQLConnection>();

      connectFunction().timeout(connectTimeout).then((conn) {
        _databaseConnection = conn;
        _pendingConnectionCompleter.complete(_databaseConnection);
        _pendingConnectionCompleter = null;
      }).catchError((e) {
        _pendingConnectionCompleter.completeError(new QueryException(
            QueryExceptionEvent.connectionFailure,
            underlyingException: e));
        _pendingConnectionCompleter = null;
      });
    }

    return _pendingConnectionCompleter.future;
  }

  return _databaseConnection;
}