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To: Alexander Korotkov <aekorotkov@gmail.com>
cc: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: WIP: Fast GiST index build 
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Comments: In-reply-to Alexander Korotkov <aekorotkov@gmail.com>
	message dated "Fri, 08 Jul 2011 13:32:39 +0400"
Date: Fri, 08 Jul 2011 10:18:05 -0400
Message-ID: <26338.1310134685@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Alexander Korotkov <aekorotkov@gmail.com> writes:
> I found that results of previous tests with USNOA2 were not fully correct.
> Tables for tests with various parameters contained tuples in different
> order. I assumed that query
> CREATE TABLE tab2 AS (SELECT * FROM tab1);
> creates tab2 as exact copy of tab1, i.e. tab2 contain tuples in same order
> as tab1. But actually, it isn't always so. In aggregate with only few used
> test cases it can cause significant error.

For test purposes, you could turn off synchronize_seqscans to prevent
that.

			regards, tom lane