Re: Data Block Cleanup??

From: PAYNE P W <gzz_at_ornl.gov>
Date: Tue, 5 Oct 1993 21:04:40 GMT
Message-ID: <1993Oct5.210440.25864_at_ornl.gov>


In article <CEFFu2.BMz_at_world.std.com> edwards_at_world.std.com (Jonathan Edwards) writes:
>In article <1OJHB6OU_at_gwdu03.gwdg.de> plewe_at_dl.mpi-dortmund.mpg.de (J.Plewe) writes:
>>: We experienced the same thing. An ORACLE field technician told us this
>>: is known as a lazy cleanup. The block header information is not "cleaned
>>: up" until the select after the insert or update that caused it to be
>>: updated. He did not say exactly what in the header was being cleaned
>>: up, but the old transaction entry would seem to be a reasonable guess.
>>
>>To my information, this is completely right.
>>
>
>Does this apply even to blocks that are memory-resident at transaction
>completion? Surely this cleanup could be done then, or at worst when the
>block gets purged. This extra step should only be necessary for blocks
>already purged at transaction completion.
>
>
I've been told by support personnel that when data is deleted and a block is ready to be added back to the free list, that this cleanup will not be done until the next time the block is selected. We experienced this when we deleted a large number of rows and the next export of that table took about 20 times what it usually does. I now routinely perform "select count(*)" on all my dynamic tables at night a couple of times a week to be sure this clean up doesn't interfere with daily work.

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Payne
Data Systems Research & Development
Oak Ridge, TN Received on Tue Oct 05 1993 - 22:04:40 CET

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