Re: PG writes a lot to the disk

From: "Laurent Raufaste" <analogue(at)glop(dot)org>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: PG writes a lot to the disk
Date: 2008-03-21 13:45:28
Message-ID: 669dc9710803210645m530b492cs6de98f215bcecb23@mail.gmail.com
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2008/3/21, Gregory Stark <stark(at)enterprisedb(dot)com>:
>
> Well that's true it does. But only once per row. So analyze would have set the
> bit on every row. You could do the same thing with something ligter like
> "select count(*) from <table>".

Well, the table has been analyzed, I did SELECT, PG write on the
table. That's a fact.

But it's also true (I juste tested it) that every file of a table is
modified by a SELECT COUNT.
>
> Tom's thinking was that you would only expect a high update rate for a short
> time until all those bits were set.
>
> Slony's inserts, updates, and deletes count as updates to the table as well.
>

Slony is shut down when I'm testing.

--
Laurent Raufaste
<http://www.glop.org/>

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