From: Gauri Kanekar <meetgaurikanekar@gmail.com>
To: Pavan Deolasee <pavan.deolasee@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Shane Ambler <pgsql@sheeky.biz>
Cc: Alvaro Herrera <alvherre@commandprompt.com>
Cc: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Replication Syatem
Date: Wed, 30 Apr 2008 22:17:46 +0530
Message-ID: <7e4ba9550804300947q7ba316c5uc95f2b2249ffbb33@mail.gmail.com> (raw)
In-Reply-To: <2e78013d0804300915u32b9a190k86496c02dba7babd@mail.gmail.com>
References: <7e4ba9550804280638ie81dc23w472785c83cd38fcf@mail.gmail.com>
<4817514A.3060704@Sheeky.Biz>
<7e4ba9550804292229x82e74e5y355349866c72245c@mail.gmail.com>
<2e78013d0804292237l4c74a166u4ab082901aa0804f@mail.gmail.com>
<7e4ba9550804292239n668b1f01v59ad7ac6ca9e092b@mail.gmail.com>
<2e78013d0804292343hd9d1c0lf93df68e559f9af3@mail.gmail.com>
<7e4ba9550804292346r46aa55e7g6cf1f731b6be7d40@mail.gmail.com>
<2e78013d0804300025j10567a82x5845ab8bc3d4f2a2@mail.gmail.com>
<18684.1209566788@sss.pgh.pa.us>
<2e78013d0804300915u32b9a190k86496c02dba7babd@mail.gmail.com>
We have tried fillfactor for indices and it seems to work.
Need to try fillfactor for table. May for that reason the bulk update
queries don't get the advantage of HOT
:)
On Wed, Apr 30, 2008 at 9:45 PM, Pavan Deolasee <pavan.deolasee@gmail.com>
wrote:
> On Wed, Apr 30, 2008 at 8:16 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > "Pavan Deolasee" <pavan.deolasee@gmail.com> writes:
> > > That's weird. With that fillfactor, you should have a very high
> > > percentage of HOT update ratio. It could be a very special case that
> > > we might be looking at.
> >
> > He's testing
> >
>
> It's "She" :-)
>
> Oh yes. Apologies if I sounded harsh; did not mean that. I was just
> completely confused why she is not seeing the HOT updates.
>
> > >> update table1 set delta1 = 100 where code/1000000 =999;
> >
> > so all the rows being updated fall into a contiguous range of "code"
> > values. If the table was loaded in such a way that those rows were
> > also physically contiguous, then the updates would be localized and
> > would very soon run out of freespace on those pages.
> >
>
> Yeah, that seems like the pattern. I tested with the similar layout
> and a fill factor 80. The initial few bulk updates had comparatively
> less HOT updates (somewhere 20-25%), But within 4-5 iterations of
> updating the same set of rows, HOT updates were 90-95%. That's because
> after few iterations (and because of non-HOT updates) the tuples get
> scattered in various blocks, thus improving chances of HOT updates.
>
> I guess the reason probably is that she is using fill factor for
> indexes and not heap, but she hasn't yet confirmed.
>
> Thanks,
> Pavan
>
> --
> Pavan Deolasee
> EnterpriseDB http://www.enterprisedb.com
>
--
Regards
Gauri
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Cc: meetgaurikanekar@gmail.com, pavan.deolasee@gmail.com, tgl@sss.pgh.pa.us, pgsql@sheeky.biz, alvherre@commandprompt.com, gsmith@gregsmith.com
Subject: Re: Replication Syatem
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