Subject: Re: Help tuning postgres
From: Csaba Nagy <nagy@ecircle-ag.com>
To: Andrew Sullivan <ajs@crankycanuck.ca>
Cc: postgres performance list <pgsql-performance@postgresql.org>
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Date: Thu, 13 Oct 2005 10:15:03 +0200
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[snip]
> Yes, but it could be a disk issue because you're doing more work than
> you need to.  If your UPDATEs are chasing down a lot of dead tuples,
> for instance, you'll peg your I/O even though you ought to have I/O
> to burn.

OK, this sounds interesting, but I don't understand: why would an update
"chase down a lot of dead tuples" ? Should I read up on some docs, cause
I obviously don't know enough about how updates work on postgres...

And how would the analyze help in finding this out ? I thought it would
only show me additionally the actual timings, not more detail in what
was done...

Thanks,
Csaba.