protected function lockSession(string $sessionID): bool
	{
		if ($this->platform === 'mysql')
		{
			$arg = md5($sessionID . ($this->matchIP ? '_' . $this->ipAddress : ''));
			if ($this->db->query("SELECT GET_LOCK('{$arg}', 300) AS ci_session_lock")->getRow()->ci_session_lock)
			{
				$this->lock = $arg;
				return true;
			}

			return $this->fail();
		}
		elseif ($this->platform === 'postgre')
		{
			$arg = "hashtext('{$sessionID}')" . ($this->matchIP ? ", hashtext('{$this->ipAddress}')" : '');
			if ($this->db->simpleQuery("SELECT pg_advisory_lock({$arg})"))
			{
				$this->lock = $arg;
				return true;
			}

			return $this->fail();
		}

		// Unsupported DB? Let the parent handle the simplified version.
		return parent::lockSession($sessionID);
	}