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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Kelly Burkhart <kelly@tradebotsystems.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: 8.x index insert performance
Date: Fri, 11 Nov 2005 18:02:11 -0500
Message-ID: <22258.1131750131@sss.pgh.pa.us> (raw)
In-Reply-To: <1131749305.14024.32.camel@krb06.tradebot.com>
References: <6EE64EF3AB31D5448D0007DD34EEB3417DD725@Herge.rcsinc.local>
	<20051031193547.GA3311@mark.mielke.cc>
	<18647.1130790629@sss.pgh.pa.us>
	<1130792391.7026.55.camel@krb06.tradebot.com>
	<19065.1130793527@sss.pgh.pa.us>
	<1130852029.7026.88.camel@krb06.tradebot.com>
	<24845.1130852730@sss.pgh.pa.us>
	<1131660117.7514.57.camel@krb06.tradebot.com>
	<13167.1131668008@sss.pgh.pa.us>
	<1131749305.14024.32.camel@krb06.tradebot.com>

Kelly Burkhart <kelly@tradebotsystems.com> writes:
> On Thu, 2005-11-10 at 19:13 -0500, Tom Lane wrote:
>> Kelly, could there be any patterns in the data that might be
>> related?

> I modified my original program to insert generated, sequential data.
> The following graph shows the results to be flat:
> <http://kkcsm.net/pgcpy_20051111_1.jpg;
> Thus, hardware is sufficient to handle predictably sequential data.

Yeah, inserting sequentially increasing data would only ever touch the
right-hand edge of the btree, so memory requirements would be pretty low
and constant.

> There very well could be a pattern in the data which could affect
> things, however, I'm not sure how to identify it in 100K rows out of
> 100M.

I conjecture that the problem areas represent places where the key
sequence is significantly "more random" than it is elsewhere.  Hard
to be more specific than that though.

			regards, tom lane



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