void PostgreSQLDatabase::Open()
  {
    if (pg_ != NULL)
    {
      switch (PQstatus(reinterpret_cast<PGconn*>(pg_)))
      {
        case CONNECTION_OK:
          // Already connected and CONNECTION_OK
          return;

        default:
          // connection not ok
          PQreset(pg_);
          if(PQstatus(reinterpret_cast<PGconn*>(pg_)) == CONNECTION_OK)
          {
            LOG(INFO) << "Reconnected to the database";
            return;
          }
          else
          {
            LOG(WARNING) << "Reconnection did not immediatelly return an OK connection";
            PQfinish(reinterpret_cast<PGconn*>(pg_));
          }
          break;
      }
    }

    std::string s;
    parameters_.Format(s);

    if (pg_) PQfinish(reinterpret_cast<PGconn*>(pg_));
    pg_ = PQconnectdb(s.c_str());

    if (pg_ == NULL ||
        PQstatus(reinterpret_cast<PGconn*>(pg_)) != CONNECTION_OK)
    {
      std::string message;

      if (pg_)
      {
        message = PQerrorMessage(reinterpret_cast<PGconn*>(pg_));
        PQfinish(reinterpret_cast<PGconn*>(pg_));
        pg_ = NULL;
      }

      LOG(ERROR) << "PostgreSQL error: " << message;
      throw Orthanc::OrthancException(Orthanc::ErrorCode_DatabaseUnavailable);
    }
  }