Re: Postres dilemma - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Postres dilemma
Date
Msg-id 23607.1086579558@sss.pgh.pa.us
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In response to Re: Postres dilemma  ("Joshua D. Drake" <jd@commandprompt.com>)
Responses Re: Postres dilemma
List pgsql-hackers
"Joshua D. Drake" <jd@commandprompt.com> writes:
> Why are you running a vacuum every 45 seconds? Increase your fsm_pages and
> run it every hour.

If I understood his description correctly, he's turning over 10% of a
500-row table every minute.  So waiting an hour would mean 3000 dead
rows in a 500-live-row table, which seems excessive.  I'd agree with
running a vacuum on this specific table every five minutes or so.

Given that he is doing more than enough vacuums, I think that the
problem is probably not table bloat, but index bloat (ie, from a
constantly shifting range of live index keys, which pre-7.4 btrees
didn't handle well at all).  This is just speculation though, without
proof as yet.
        regards, tom lane


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