From: | Vadim Mikheev <vadim(at)krs(dot)ru> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Edmund Mergl <E(dot)Mergl(at)bawue(dot)de>, PostgreSQL Hackers Mailinglist <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: [HACKERS] strange behavior of UPDATE |
Date: | 1999-05-26 02:45:30 |
Message-ID: | 374B604A.2607A30C@krs.ru |
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Lists: | pgsql-hackers |
Tom Lane wrote:
>
> Those are attention-getting numbers, all right. I think that the two
> equal-key problems I found last night might partially explain them;
> I suspect there are more that I have not found, too. I will look into
> it some more.
Am I correct that update takes ~ 10% CPU with high disk activity?
(Unfortunately, no list archive after May 13, so I'm not able
to re-read thread).
Remember that update inserts new index tuples and most likely
index scan will see these tuples and fetch just inserted
heap tuples.
> Could you try the same queries with no indexes in place, and see what
> the time scaling is like then? That would confirm or deny the theory
> that it's an index-update problem.
>
> Question for the hackers list: are we prepared to install purely
> performance-related bug fixes at this late stage of the 6.5 beta cycle?
> Bad as the above numbers are, I hesitate to twiddle the btree code and
> risk breaking things with only a week of testing time to go...
Try to fix problems and run Edmund scripts to see are things
better than now. We can apply fixes after 6.5.
Vadim
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