From: | "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com> |
---|---|
To: | pginfo <pginfo(at)t1(dot)unisoftbg(dot)com> |
Cc: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: slow vacuum performance |
Date: | 2004-03-24 18:13:55 |
Message-ID: | Pine.LNX.4.33.0403241111090.1456-100000@css120.ihs.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
On Wed, 24 Mar 2004, pginfo wrote:
> Hi,
>
> scott.marlowe wrote:
>
> > On Wed, 24 Mar 2004, pginfo wrote:
> >
> > > Hi,
> > >
> > > I am running pg 7.4.1 on linux box.
> > > I have a midle size DB with many updates and after it I try to run
> > > vacuum full analyze.
> >
> > Is there a reason to not use just regular vacuum / analyze (i.e. NOT
> > full)?
> >
>
> Yes, in case I make massive updates (only in my case of cource) for example
> 2 M rows, I do not expect to have 2M new rows in next 180 days.That is the
> reaso for running vacuum full.
> My idea was to free unneedet space and so to have faster system.
> It is possible that I am wrong.
It's all about percentages. If you've got an average of 5% dead tuples
with regular vacuuming, then full vacuums won't gain you much, if
anything. If you've got 20 dead tuples for each live one, then a full
vacuum is pretty much a necessity. The generally accepted best
performance comes with 5 to 50% or so dead tuples. Keep in mind, having a
few dead tuples is actually a good thing, as your database won't grow then
srhink the file all the time, but keep it in a steady state size wise.
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