Out of order in tpdequeue

Question

We have an application that has a sequentiality constraint. It seems that when
we do to tpenqueues within a single transaction, the single process that does
the tpdequeue sometimes gets the messages in a different order than they were
actually dequeued. Consider the following pseudo code snippet:
tpbegin();
tpenqueue(someqspace, someque,message1);
tpenqueue(thesameqspace, thesameque,message2);
tpcommit();
Can we always expect message1 to be dequeued before message2. assuming that there
is only one process dequeueing from the queue? If not, why not?
TIA...

Answer 1

Apologies - addition below to point 2
"Aviral" <[email protected]> wrote:
>
Scott,
The queue is a FIFO queue. The verbose output of the queue is as below:
Queue QRouterS: 0 Persistent Messages using 0 pages.
0 Nonpersistent Messages using 0 bytes.
0 Messages in total using 0 bytes.
Queue order: fifo
Out of order: none
Retries: 100
Delay: 0
Default delivery policy: persist
Default expiration time: none
Threshold Triggers:
Persistent: 0 - 80 %, Command: null
Non-persistent: 0 - 100 %, Command:
Some other points:
1) There are multiple processes writing to the queue all the time
2) There are only two processes writing multiple messages to this queue
at the same time within a transaction.
3) There is a tmqforward (specially written) on the queue which is peeking
at
the queue and if it finds something, dequeues the message after starting
the transaction.
4) Emperical data suggests that about 80% of the time the messages (in
case of
2 in a transaction) are being read in the reverse order.
5) We do not set birth times.
We are unable to duplicate this behaviour in developement.
Thank you very much in advance for any direction you can point us in.
Regards,
Aviral.
Scott Orshan <[email protected]> wrote:
If you have a FIFO queue, and do not set birth times, the messages should
come out
in order. You would need to post the queue creation script, as wellas
some of the
code you are using to dequeue the messages.
Are you dequeuing within a transaction as well? After the enqueues,can
you list
the queue and see the messages in the correct order?
     Scott Orshan
Alex Wolfson wrote:
We have an application that has a sequentiality constraint. It seemsthat when
we do to tpenqueues within a single transaction, the single processthat does
the tpdequeue sometimes gets the messages in a different order thanthey were
actually dequeued. Consider the following pseudo code snippet:
tpbegin();
tpenqueue(someqspace, someque,message1);
tpenqueue(thesameqspace, thesameque,message2);
tpcommit();
Can we always expect message1 to be dequeued before message2. assumingthat there
is only one process dequeueing from the queue? If not, why not?
TIA...