Hi All,

I have a trivial task. There is a table with messages queue, let's say "msg_queue". There are a few processes and each of them is taking one message from this table at a time to transmit into communication channel. I've done it my way, but I have postgresql's messages about deadlocks and a lot of warnings.

I my program, every process is doing approx the following procedure:
SELECT ... FROM msg_queue WHERE busy = false ORDER BY ... LIMIT 1;
if a message was found:
BEGIN;
SELECT id FROM msg_queue WHERE id = ... AND busy = false FOR SHARE;
UPDATE msg_queue SET busy = true, channel_id = ... WHERE id = ... AND busy = false;
COMMIT;


I do understand that this way is stupid, but I have not came with anything else yet. Could somebody share ideas how to do this so the same message 100% WOULD NOT be transmitted over two or more channels.
Sorry for the newbie question!

Best regards, Nick.

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