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| Scratchpad object |
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| mgrabinski |
 Posted: Wed Jul 07, 2004 1:04 am Post subject: Scratchpad object |
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Master
Joined: 16 Oct 2001
Posts: 246
Location: Katowice, Poland
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Starting from version 5, MQSeries uses a so called scratchpad object to store information concerning channel status. In earlier versions a synchronization queue was used for that purpose. I know the function of the scratchpad object, but I lack the basics - what is it? Is it a file? Where is it stored?
TIA
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Marcin Grabinski <>< |
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| JasonE |
| Posted: Wed Jul 07, 2004 1:32 am Post subject: |
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Grand Master
Joined: 03 Nov 2003
Posts: 1220
Location: Hursley
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Roughly stating, its a file for a channel which is not in an inactive state, which contains things like the sequence numbers sent and confirmed. It does contain more, but thats the basics. The files are the %CHLBATCH files.
Pre scratchpads, (roughtly) everytime we changed the sequence number we had to write a message to an MQ queue, which is overkill. Now we do a simple file update, and only put the data back into the syncq when the channel goes into certain states.
As I said this is not 100% accurate, but a good approximation... |
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| mgrabinski |
| Posted: Wed Jul 07, 2004 2:30 am Post subject: |
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Master
Joined: 16 Oct 2001
Posts: 246
Location: Katowice, Poland
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Thank you for your clarification. But it has prompted me to ask further questions 
I assume that the scratchpad object is an internal one and that the MQ admin has nothing to do with it. Is it correct? If not, are there any hidden commands or tools to view and manage it? Is there anything to tune?
In what
is there a need to synchronize the sratchpad obejct and the SYNC queue?
What happens to scratchpad objects if the SYNC queue is purged?
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Marcin Grabinski <>< |
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| JasonE |
| Posted: Wed Jul 07, 2004 4:43 am Post subject: |
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Grand Master
Joined: 03 Nov 2003
Posts: 1220
Location: Hursley
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Its purely internal and there should be no reason to know about the files and there are no commands to directly manipulate it. Being purely internal, there is nothing we would externalize in the way of tools either (assuming we had tools internally as well!).
The deal is (roughly) that all the time a channel status entry is allocated, then the scratchpad contains the sync info, and when the status entry is removed, that data has been hardened onto the syncq.
Purging syncq's...? Hmmm, I've no idea - Not something that springs to mind as a good idea though |
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