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| Why is SYSTEM.RETAINED.PUB.QUEUE filling with dupl msgs? |
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| t603 |
 Posted: Wed Jun 15, 2016 7:14 am Post subject: Why is SYSTEM.RETAINED.PUB.QUEUE filling with dupl msgs? |
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Voyager
Joined: 16 Oct 2012
Posts: 88
Location: Prague, the Czech Republic, Europe
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Hello,
I have facing a strange problem for me in MQ 7.5.n. I enables StatisticsAccount in IIB in Archive mode ("mqsichangeflowstats BK1 -a -g -j -c active -o xml -n none -t none -r"), then created a topic MyObj ("$SYS/Broker/BK1/StatisticsAccounting/Archive/#"), then created a subscription MyObj ("$SYS/Broker/BK1/StatisticsAccounting/Archive/#" pointing to the local queue MyObj). Yes, all three objects with the same name to be able easy find the problem in logs. All these objects I created in MQ Explorer 8.0 with as many default values, as possible.
Well, my queue MyObj is full of wanted messages as desired... but the same messages are also in SYSTEM.RETAINED.PUB.QUEUE. And this is the problem for me! I want to get messages from MyObj queue, but I do not want to clean up SYSTEM.RETAINED.PUB.QUEUE.
Why are these messages in SYSTEM.RETAINED.PUB.QUEUE? I suppose, that this queue is filled by messages in case, that registered subscriber is not available for some time, so these messages are kept there until the subscriber is available again. But it is not my case, because MyObj subscription contains the same messages. I reviewed display (queue, sub)status and the last puts are the same to bot queues (MyObj and S.R.P.Q). Even I reviewed topic MyObj, if there is any other subscription, but not.
Can I ask You for help, how to avoid of such unwanted filling of SYSTEM.RETAINED.PUB.QUEUE? Some parameter of topic or subscription?
Thank You in advance, Stepan |
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| t603 |
| Posted: Wed Jun 15, 2016 10:45 am Post subject: |
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Voyager
Joined: 16 Oct 2012
Posts: 88
Location: Prague, the Czech Republic, Europe
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Well, I have Googled again and maybe found the answer.
On https://www.ibm.com/support/knowledgecenter/SSFKSJ_8.0.0/com.ibm.mq.pro.doc/q004940_.htm is written:
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| The queue manager can retain only one publication for each topic, so the existing retained publication of a topic is deleted when a new retained publication arrives at the queue manager. |
So it means, that the output (publishing) of "mqsichangeflowstats" is published as "retained" - avaiable for future possible subscribers and, what is crucial for me, once for each message flow StatisticsAccounting message only most up-to-date message is kept in SYSTEM.RETAINED.PUB.QUEUE. So using some MQ Server internal mechanism in one transaction the old message is deleted once new message arrived for each particular message flow.
So I should not worry about the number of StatisticsAccounting messages in SYSTEM.RETAINED.PUB.QUEUE, because there can not me never more than the number of my message flows (1.300 in my case), which has StatisticsAccounting enabled (or twice in case both SnapShot and Archive type).
Am I right? Stepan |
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| hughson |
| Posted: Wed Jun 15, 2016 2:07 pm Post subject: |
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Padawan
Joined: 09 May 2013
Posts: 1967
Location: Bay of Plenty, New Zealand
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You are correct, that is how retained publications work. And you shouldn't worry about it.
_________________
Morag Hughson @MoragHughson
IBM MQ Technical Education Specialist
Get your IBM MQ training here!
MQGem Software |
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| bruce2359 |
| Posted: Wed Jun 15, 2016 7:52 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9486
Location: US: west coast, almost. Otherwise, enroute.
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| hughson wrote: |
| You are correct, that is how retained publications work. And you shouldn't worry about it. |
Retained publications is an option. If there is no business requirement for it, don't use it.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| hughson |
| Posted: Wed Jun 15, 2016 8:39 pm Post subject: |
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Padawan
Joined: 09 May 2013
Posts: 1967
Location: Bay of Plenty, New Zealand
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| bruce2359 wrote: |
| Retained publications is an option. If there is no business requirement for it, don't use it. |
It's an option chosen by the publisher, which in this case is the broker producing the statistics information. If there's a way to turn it off it would be a broker setting.
_________________
Morag Hughson @MoragHughson
IBM MQ Technical Education Specialist
Get your IBM MQ training here!
MQGem Software |
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