You can add a LIMIT n to your update clause. Regards, Gavin Towey
-----Original Message----- From: Allen Fowler [mailto:allen.fow...@yahoo.com] Sent: Monday, September 07, 2009 5:18 PM To: mysql@lists.mysql.com Subject: Queue / FIFO in MySQL? Hello, I need to create a system where records are generated by a "producer" process and processed by several "worker" processes. I was thinking about something like: Producer: 1) Producer INSERTs new records with "state" = "new" & "worker" = "null" 2) Producer sleeps and loops back to step #1 Worker(s): 1) Worker UPDATEs all records with "worker" = "pid" & "state" = "working" where "state" == "new" 2) Worker SELECTs all records where "worker" = "pid" & "state" = "working" 3) For each record that is done, worker updates record with "state" = "done" 4) Worker loops back to step #1 Note: In this scheme the worker winds up with all "new" records generated since the last worker claimed any. Not sure how else to guarantee atomicity. I would prefer "only n records per request". Ideas? I am sure something like this must have been before.... Can anyone point me to example code, libraries, and/or refinements on the scheme? (preferably using python...) Thank you, :) -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=gto...@ffn.com The information contained in this transmission may contain privileged and confidential information. It is intended only for the use of the person(s) named above. If you are not the intended recipient, you are hereby notified that any review, dissemination, distribution or duplication of this communication is strictly prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
