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| MQWays |
 Posted: Tue Apr 29, 2008 2:25 am Post subject: Circular Queue |
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Acolyte
Joined: 20 Jan 2008
Posts: 61
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| Just like circular logs, is there something like circular queue. For e.g. if the MAXDEPTH on the queue is set to 1000, every subsequent put after hitting the limit should execute successfully in FIFO manner i.e. purging out the oldest message. |
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| AkankshA |
| Posted: Tue Apr 29, 2008 2:29 am Post subject: |
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Grand Master
Joined: 12 Jan 2006
Posts: 1494
Location: Singapore
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never heard about such a queue
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| Vitor |
| Posted: Tue Apr 29, 2008 2:31 am Post subject: Re: Circular Queue |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| MQWays wrote: |
| Just like circular logs, is there something like circular queue. |
No.
The queues are not design to hold information long term so messages shouldn't build up. Certainly there's a risk (in the scenario you quote) that the assured delivery model of WMQ would be broken. If the oldest message was persistent & unread, it would be lost before it was processed despite being accepted for delivery by WMQ.
It sounds like what you need is to set message expiry to some value equal to maximum time the message has a value to the business, or use durable subscriptions to obtain the latest copy of a given message.
But I could be hearing your requirement wrong.
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Insanity is the best defence. |
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| Gaya3 |
| Posted: Tue Apr 29, 2008 2:39 am Post subject: |
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Jedi
Joined: 12 Sep 2006
Posts: 2493
Location: Boston, US
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you can learn circular queue in the Data Structure Book.
there is no concept of circular queue here...
Regards
Gayathri
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| fjb_saper |
| Posted: Tue Apr 29, 2008 3:31 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Are you trying to mimick a publication with retention?
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MQ & Broker admin |
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| mvic |
| Posted: Tue Apr 29, 2008 3:49 am Post subject: Re: Circular Queue |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| MQWays wrote: |
| Just like circular logs, is there something like circular queue. For e.g. if the MAXDEPTH on the queue is set to 1000, every subsequent put after hitting the limit should execute successfully in FIFO manner i.e. purging out the oldest message. |
Interested to know what requirements lead to this design being considered. |
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| jefflowrey |
| Posted: Tue Apr 29, 2008 3:50 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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If one could rely on the rate at which messages are put to the queue, one could rely on expiration to remove messages from the queue.
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| Vitor |
| Posted: Tue Apr 29, 2008 3:50 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| fjb_saper wrote: |
| Are you trying to mimick a publication with retention? |
 I meant that!
Why my fingers typed "durable subscription", which is something else again, is anyone's guess.
(Guesses containing the concept "you're an idiot" may be close to the truth!)
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Insanity is the best defence. |
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| mdncan |
| Posted: Tue Apr 29, 2008 7:04 am Post subject: |
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Acolyte
Joined: 11 May 2005
Posts: 59
Location: US
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It doesn't make sense to compare the logging vs queue depth, net sure what's your business requirement? You should look at other alternates viz., increasing the max depth and creating cluster of applications to read and process the messages. if the queue is audit queue then you can purge them at the end of the day.
Pl. post your requirement so that people can understand better and advice on it.
Thnx
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| MQWays |
| Posted: Tue Apr 29, 2008 9:48 pm Post subject: |
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Acolyte
Joined: 20 Jan 2008
Posts: 61
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My main requirement is to use the mirrorq utility to facilitate maintaining a copy of the posted message on separate queue. However to avoid regular maintenance of the queue, I prefer setting up the MAXDEPTH lets say to 3000 and then let it roll-over in circular fashion.
So at any point in time, I would be able to retrieve last 3000 messages for any required investigation, retrieve a copy of any lost message in transit or keep it as proof of a successful MQ Post to the infrastructure guys. |
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| Vitor |
| Posted: Wed Apr 30, 2008 12:41 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| MQWays wrote: |
| So at any point in time, I would be able to retrieve last 3000 messages for any required investigation, retrieve a copy of any lost message in transit or keep it as proof of a successful MQ Post to the infrastructure guys. |
This has been discussed a few times in here. To sumarise the main points:
- WMQ is a bad place to store data. If you need to keep messages, insert them into a database (which is easier to clear out based on message age)
- Auditing should be performed in the application layer. Successful get or put should be recorded by the application in a log
- Properly configured & monitored WMQ installations do not lose messages in transit, despite about 80% of project managers believing they do. The resources used for this kind of "just in case" message logging are better spent on perfecting the configuration & proper monitoring.
A search will turn up many discussions expanding these points.
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Honesty is the best policy.
Insanity is the best defence. |
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| zpat |
| Posted: Wed Apr 30, 2008 1:06 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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| Using expiry on messages would achieve much the same effect. |
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| PeterPotkay |
| Posted: Wed Apr 30, 2008 7:02 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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...assuming a very consistent input rate of new messages to maintain ~ 3000 messages.
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Keep Calm and MQ On |
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