public function unlock()
{
$readDsId = $this->readSourceId;
$writeDsId = $this->writeSourceId;
if ($readDsId === $writeDsId) {
$this->getReadConnection()->query('UNLOCK TABLES;');
} else {
$this->getReadConnection()->query('UNLOCK TABLES;');
$this->getWriteConnection()->query('UNLOCK TABLES;');
}
}