From: | Markus Schiltknecht <markus(at)bluegap(dot)ch> |
---|---|
To: | Gokulakannan Somasundaram <gokul007(at)gmail(dot)com> |
Cc: | Gregory Stark <stark(at)enterprisedb(dot)com>, pgsql-hackers list <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Some ideas about Vacuum |
Date: | 2008-01-10 11:01:36 |
Message-ID: | 4785FB10.8030800@bluegap.ch |
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Lists: | pgsql-hackers |
Hi,
Gokulakannan Somasundaram wrote:
> because of the contention. Am i missing something
> here? While Vacuum is reading the DSM, operations may not be able to
> update the bits. We need to put the DSM in shared memory, if all the
> processes are going to update it, whereas if Vacuum is going to form the
> DSM, then it might well be in the process local memory. I can think of
> things like False sharing which might be avoided. But i think the main
> stuff is contention.
Ah, I begin to understand where you are coming from now, yes. However,
(ab-)using the WAL and archiver still doesn't look like a good idea to me.
> Even in indexes, we might end up reading dead tuples. We would mark it
> with LP_DEAD. So the overhead is less, but its there.
That's a good point, yes.
> Ofcourse its
> natural to think of some background jobs during OLTP, and they will be
> affected
Agreed.
Regards
Markus
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