public function loadOids($file)
    {
        if (!file_exists($file)) {
            throw $this->createException('OIDs cache file not found');
        }

        if ($this->oidTypeNames) {
            return $this;
        }

        if (!$this->host || !$this->dbName) {
            throw $this->createException('You must set host name and dbName first');
        }

        $oids = include $file;

        if (isset($oids[$this->host][$this->dbName])) {
            $this->oidTypeNames = $oids[$this->host][$this->dbName];
        }

        return $this;
    }