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MQSeries.net Forum Index » General IBM MQ Support » qfile - message duplication?

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sac063
PostPosted: Wed Jan 25, 2006 11:55 am    Post subject: qfile - message duplication? Reply with quote

Apprentice

Joined: 23 Jan 2004
Posts: 36

Hi All,

Read quiet a few discussions on qfile, log buffers and mq logs. I have the below assumption -

"If a message is written to the queue and there is an MQCOMMIT, it is also written tot the mq log. Whereas if the message is pulled off from the queue by an external application but there is no COMMIT yet, then it is held is qfile"

If I am right, is the use of qfile only to save space on logs for uncommitted messages?

Also If I restart the QM, do I lose any message or more importantly end up placing a message that is already pulled off by the application leading to duplication?

Thanks....
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wschutz
PostPosted: Wed Jan 25, 2006 3:07 pm    Post subject: Reply with quote

Jedi Knight

Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)

Quote:
Also If I restart the QM, do I lose any message or more importantly end up placing a message that is already pulled off by the application leading to duplication?
If the messages are persistent and committed, they will not be lost due to qmgr failure or restart. MQ will not duplicate messages, providing the "getting"" application plays by the rules (ie, gets the message under syncpoint control and commits at the appropiate time).

You query about log and q usages has been answered elsewhere in this forum.
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sac063
PostPosted: Thu Jan 26, 2006 12:04 am    Post subject: Reply with quote

Apprentice

Joined: 23 Jan 2004
Posts: 36

Thanks for the quick response.

Quote:
MQ will not duplicate messages, providing the "getting"" application plays by the rules (ie, gets the message under syncpoint control and commits at the appropiate time).


If this is the case, I understand that it is the responsibility of the application to put the message back into the queue if the transaction is not successful. This is precisely what is happening.

But then, why does MQ store these uncommitted messages in the qfile? Does it use this message store somewhere?
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