Re: Query optimization help - Mailing list pgsql-performance

From Ondrej Ivanič
Subject Re: Query optimization help
Date
Msg-id CAM6mie+xUUB-Dv8Bw0eV1qA5kkyJD0UJtfCBbs1HpAkGC7-QTQ@mail.gmail.com
Whole thread Raw
In response to Re: Query optimization help  (Szymon Kosok <szymon@mwg.pl>)
List pgsql-performance
Hi,

2011/8/30 Szymon Kosok <szymon@mwg.pl>:
> 2011/8/30 Ondrej Ivanič <ondrej.ivanic@gmail.com>:
>> Could you please re-post your explain using this web site:
>> http://explain.depesz.com/ and post links to Stackoverflow question?
>
> Here it is: http://explain.depesz.com/s/Iaa
>
>> - try to disable nested loop join (set enable_nestloop=off)

Thanks, I would try to "materialise" spoleczniak_tablica table. Your
query looks like this:
select ...
from spoleczniak_tablica
inner join ...
where ...
order by spoleczniak_tablica.id desc
limit 21

So I would rewrite your query like this:
select ...
from (
     select ...
     from spoleczniak_tablica
     where ....
     order by spoleczniak_tablica.id desc
     limit 21
) as x
inner join ...


--
Ondrej Ivanic
(ondrej.ivanic@gmail.com)

pgsql-performance by date:

Previous
From: Szymon Kosok
Date:
Subject: Re: Query optimization help
Next
From: Grzegorz Jaśkiewicz
Date:
Subject: Re: 8.4 optimization regression?