Posted: Fri Feb 25, 2005 11:31 pm Post subject: Will Persitent message be removed From Log ?
Voyager
Joined: 27 Dec 2004 Posts: 82
Just one more doubt about the logging process..
We know that the persistent message is written in to Logs at the time of the PUT call ...
Now if i give GET call for the same message, will it be removed from the disk (is it destructive get) or will i get the copy of it and the message will still be maintained on the disk
Depends on your type of logging.
In circular logging there is only transaction safety. Your message is guaranteed only for as long as it is in a transaction i.e. covered through syncpoint (get or put). When symply residing on the queue it is not covered.
Linear logging allows for media recovery. As long as the message is on the queue it is in one of the active logs. You can reorganize the logs to free log space by running the record utility. You can then remove inactive logs.
So in essence the message gets written to the log put to the queue and when removed from the queue there is some kind of entry to the log identifying the message so that the system knows the message is no longuer on the queue. It gets never removed from the log in linear logging. In circular logging the information gets overwritten as soon as it is obsolete.
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