From: Steinar H. Gunderson <sgunderson@bigfoot.com>
To: pgsql-performance@postgresql.org
Subject: Re: Performance pb vs SQLServer.
Date: Mon, 15 Aug 2005 03:01:59 +0200
Message-ID: <20050815010159.GA27795@uio.no> (raw)
In-Reply-To: <42FFE17A.6010208@arbash-meinel.com>
References: <20050811131911.3175A1C0031B@mwinf0401.wanadoo.fr>
<42FFE17A.6010208@arbash-meinel.com>
On Sun, Aug 14, 2005 at 07:27:38PM -0500, John Arbash Meinel wrote:
> My guess is that this is part of a larger query. There isn't really much
> you can do. If you want all 3.2M rows, then you have to wait for them to
> be pulled in.
To me, it looks like he'll get 88 rows, not 3.2M. Surely we must be able to
do something better than a full sequential scan in this case?
test=# create table foo ( bar char(4) );
CREATE TABLE
test=# insert into foo values ('0000');
INSERT 24773320 1
test=# insert into foo values ('0000');
INSERT 24773321 1
test=# insert into foo values ('1111');
INSERT 24773322 1
test=# select * from foo group by bar;
bar
------
1111
0000
(2 rows)
I considered doing some odd magic with generate_series() and subqueries with
LIMIT 1, but it was a bit too weird in the end :-)
/* Steinar */
--
Homepage: http://www.sesse.net/
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To: pgsql-performance@postgresql.org
Cc: sgunderson@bigfoot.com
Subject: Re: Performance pb vs SQLServer.
In-Reply-To: <20050815010159.GA27795@uio.no>
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