Denis reported in ZF-7650 that a receive(0) didn't work properly. I started checking all of the other Zend_Queue_Db adapter and found that the Zend_Db_Select() code suffers from a similar issue as well.

Our code executes the following:

            $maxMessages = 0
            $query->from($info['name'], array('*'))
                  ->where('queue_id=?', $this->getQueueId($queue->getName()))
                  ->where('handle IS NULL OR timeout+' . (int)$timeout . ' < ' . (int)$microtime)
                  ->limit($maxMessages);

Which generates the following SQL:

SELECT `message`.* FROM `message` WHERE (queue_id=96) AND (handle IS NULL OR timeout+30 < 1251045482) FOR UPDATE

The LIMIT 0 is missing.

Which causes all values to be returned.

I tried a LIMIT 0 in MySQL, and I got the following

mysql> SELECT `message`.* FROM `message` WHERE (queue_id=96) AND (handle IS NULL OR timeout+30 < 1251045482) LIMIT 0 FOR UPDATE;
Empty set (0.00 sec)

So, LIMIT 0 does work, it doesn't make a lot of sense, but it does work.

:)

-daniel