The query is probably fine.. that is just the lock doing it's job. Take that advice literally.. when you fail with that class of exception, delay a milli-second or two and retry. For a large PHP site I designed, we had that behaviour built-in: up to three attempts waits 5, then 10 ms between trys. In spite of 1M+ user/day we rarely made it to the third attempt.
- michael dykman On Mon, Feb 1, 2010 at 9:33 AM, Dante Lorenso <da...@lorenso.com> wrote: > All, > > I am trying to create an atomic operation in MySQL that will manage a > "queue". I want to lock an item from a table for exclusive access by one of > my processing threads. I do this by inserting the unique ID of the record I > want to reserve into my "cli_lock" table. The following query is what I am > using to lock a record in my queue: > > INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt) > SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR) > FROM queue q > LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type = 'parse' > WHERE l.object_id IS NULL > AND q.status = 'parse' > ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC > LIMIT 1 > > However, as I execute this query several times each minute from different > applications, I frequently get these messages: > > DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when > trying to get lock; try restarting transaction > > Am I writing my query wrong or expecting behavior that MySQL doesn't > support? > > -- Dante > -- - michael dykman - mdyk...@gmail.com May the Source be with you. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
