Re: Performance-Tuning

From: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: Konstantinos Agouros <elwood(at)agouros(dot)de>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Performance-Tuning
Date: 2001-01-19 17:48:58
Message-ID: Pine.BSF.4.21.0101190945180.5520-100000@megazone23.bigpanda.com
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Well, since you're grouping, you don't need the distinct on (it's
sort of assumed by group by - you're only going to get one group
for each distinct value set of your grouped columns). In my
explain, this cuts out a unique step on my small tables, not
sure how significant that's going to be on an already unique
set of columns though.

On Fri, 19 Jan 2001, Konstantinos Agouros wrote:

> Hi,
>
> I have a table with the fields data(timestamp), region and url (varchar)
> This table has 4.5mio entries a day. To reduce them I use the following
> insert-statement.
>
> insert into msreduce select distinct on (region, url) '1-16-2001',region,url,count(client) from microsoftlog where date > '1-16-2001' and date < '1-17-2001' group by region,url
>
> My question: Could this be optimized?

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