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AQ: Establishing Absolute Enqueue Order [message #137405] Thu, 15 September 2005 02:21
Messages: 1
Registered: September 2005
Location: Sydney
Junior Member

I would like to know if it is possible to absolutely establish the order in which messages are enqueued onto a queue, preferably by query to the underlying queue table. My Database release is

I have found this from page 6-5 of a96587:


What is the order in which messages are dequeued if many messages are enqueued in the same second?

When the enq_time is the same for messages, there is another field called step_no that will be monotonically increasing (for each message that has the same enq_time). Hence this helps in maintaining the order of the messages. There will be no situation when both enq_time and step_no are the same for more than one message enqueued from the same session.

But what happens if I have messages being enqueued from different sessions, which I do. Is there any way of establishing which of the two messages enqueued in the same second from two different sessions was enqueued first?

I need to know this for debugging and testing purposes of time critical systems which communicate through AQ. Ideally I want to be able to review the exchange of messages which has taken place (with absolute certainty about the ordering) by querying on the (retained) mesasges in the underlying queue table.

Many thanks in advance.


[Updated on: Thu, 15 September 2005 02:22]

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