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Re: Replication Syatem

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com>
Cc: "Gauri Kanekar" <meetgaurikanekar(at)gmail(dot)com>, "Shane Ambler" <pgsql(at)sheeky(dot)biz>, "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, "Greg Smith" <gsmith(at)gregsmith(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Replication Syatem
Date: 2008-04-30 14:46:28
Message-ID: 18684.1209566788@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)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

>> 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.

			regards, tom lane

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