From: Florian Weimer <fw@deneb.enyo.de>
To: Miroslav ?ulc <miroslav.sulc@startnet.cz>
Cc: pgsql-sql@postgresql.org
Subject: Re: SELECT DISTINCT too slow
Date: Thu, 01 Jun 2006 20:59:05 +0200
Message-ID: <87d5dsn1mu.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <20060601154613.GC19388@surnet.cl>
References: <447EEAF1.7040305@startnet.cz>
<12554.1149175230@sss.pgh.pa.us>
<447F0A44.3080500@startnet.cz>
<20060601154613.GC19388@surnet.cl>
* Alvaro Herrera:
> Miroslav ?ulc wrote:
>> The GROUP BY is really fast :-)
>
> Doh! How does it do it?
It uses a hash table and can therefore discard duplicate rows more
quickly (essentially linear time in the number of rows if the number
of different rows is bounded).
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To: pgsql-sql@postgresql.org
Cc: fw@deneb.enyo.de, miroslav.sulc@startnet.cz
Subject: Re: SELECT DISTINCT too slow
In-Reply-To: <87d5dsn1mu.fsf@mid.deneb.enyo.de>
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