public function getPdo($connection = null)
	{
		if ($connection === null) {
			$connection = $this->defaultConnection;
		}

		if (isset($this->instances[$connection])) {
			return $this->instances[$connection];
		}

		$config = $this->getConnectionConfig($connection);

		return $this->instances[$connection] = $this->factory->makePdo($config, $connection);
	}