CREATE TABLE `survey_sessions_queue` (
  `unit_session_id` bigint(20) unsigned NOT NULL,
  `run_session_id` int(10) unsigned NOT NULL,
  `unit_id` int(10) unsigned NOT NULL,
  `created` int(10) unsigned NOT NULL,
  `expires` int(10) unsigned NOT NULL,
  `run` varchar(45) COLLATE utf8_unicode_ci NOT NULL,
  `counter` int(10) unsigned NOT NULL DEFAULT '0',
  `execute` tinyint(1) unsigned NOT NULL DEFAULT '1' 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

ALTER TABLE `survey_sessions_queue`
 ADD PRIMARY KEY (`unit_session_id`), ADD KEY `run_session_id` (`run_session_id`,`unit_id`), ADD KEY `expires` (`expires`);
