[rabbitmq-discuss] Mirrored queue "requeue" un-acknolwedged message in failover

Francesco Mazzoli francesco at rabbitmq.com
Thu Jul 12 17:39:00 BST 2012

Hi jimwu,
At Thu, 12 Jul 2012 09:02:58 -0700 (PDT),
jimwu  wrote:
> Wonder if RabbitMQ broker can add a "flag" attaribute to the requeued
> messages in failover, so our consumer application can see a requeued message
> comoing. I imagine this can be done in RabbitMQ. Since the broker does the
> work of requeuing already, it can (easily?) add a flag to those messges.  
> That way, our app will have an easier time to handle requeued message.

Well the issue here is that the slave does not know if the consumer has seen the
unacked messages that it will requeue. If repeated messages are unacceptable you
are going to have to do some bookkeeping on the consumer side anyway, since that
hypothetical flag would not guarantee you anything.

Are you asking for a flag like that just to make the bookkeeping less resource
intensive? In that case, I doubt it'd make much of a difference, since you are
going to have to take track of all the messages anyway - the only thing that
you'll save is the checking of some messages, but that's likely not to be the
main problem anyway.

Francesco * Often in error, never in doubt

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