src/Db/Pgsql/PgConnection.php
public function query($query): Observable
    {
        return new AnonymousObservable(
            function (ObserverInterface $observer, SchedulerInterface $scheduler = null) use ($query) {
                if ($this->connStatus === $this::CONNECTION_NEEDED) {
                    $this->start();
                }
                if ($this->connStatus === $this::CONNECTION_BAD) {
                    $observer->onError(new \Exception('Connection failed'));
                    return new EmptyDisposable();
                }

                $q = new Query($query, $observer);
                $this->commandQueue[] = $q;
                $this->changeQueueCountInc();

                $this->processQueue();

                return new CallbackDisposable(function() use ($q) {
                    $this->changeQueueCountDec();
                    if ($this->currentCommand === $q && $q->isActive()) {
                        $this->cancelRequest();
                    }
                    $q->cancel();
                });
            }
        );

    }
public function query($query): Observable
    {
        return new AnonymousObservable(
            function (ObserverInterface $observer, SchedulerInterface $scheduler = null) use ($query) {
                if ($this->connStatus === $this::CONNECTION_NEEDED) {
                    $this->start();
                }
                if ($this->connStatus === $this::CONNECTION_BAD) {
                    $observer->onError(new \Exception('Connection failed'));
                    return new EmptyDisposable();
                }

                $q = new Query($query, $observer);
                $this->commandQueue[] = $q;
                $this->changeQueueCountInc();

                $this->processQueue();

                return new CallbackDisposable(function() use ($q) {
                    $this->changeQueueCountDec();
                    if ($this->currentCommand === $q && $q->isActive()) {
                        $this->cancelRequest();
                    }
                    $q->cancel();
                });
            }
        );

    }
Execute simple query
@param string $query
@return Observable