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Re: Re: dramatic slowdown. . .fixed by vacuum

From: The Hermit Hacker <scrappy(at)hub(dot)org>
To: Joe Slag <jslag(at)visi(dot)com>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: Re: dramatic slowdown. . .fixed by vacuum
Date: 2000-07-21 20:20:23
Message-ID: Pine.BSF.4.21.0007211719240.325-100000@thelab.hub.org (view raw or flat)
Thread:
Lists: pgsql-novice
On Fri, 21 Jul 2000, Joe Slag wrote:

> On Fri, Jul 21, 2000 at 12:36:35PM -0700, WOLF, PATRICK wrote:
> > Try running vacuum on the table or the database.  Here's an excerpt from the
> > man on vacuum:
> > 
> [snip]
> > 
> > 
> 
> Thanks to all who responded.  I vacuumed out foo, and sure enough 
> the select time is down to 10 seconds again.
> 
> I see in the docs the suggestion: 
> 
>     We recommend that active production databases be VACUUMM-ed nightly
> 
> Is this how people tend to do their vacuuming?  Does anyone do programmatic
> vacuums instead of / in addition to a nightly run?  Is vacuuming mainly
> necessary after big deletes, or are there other common situations 
> requiring it?

UPDATEs are a combination of 'INSERT new tuple/mark old as DELETEd', so
for each UPDATE, you are adding one more tuple to the table but not
removing anything.  VACUUM removes that DELETEd tuple.  



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Subject: Re: Re: dramatic slowdown. . .fixed by vacuum
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