Re: Performance of full outer join in 8.3 - Mailing list pgsql-general

From Christian Schröder
Subject Re: Performance of full outer join in 8.3
Date
Msg-id 49E5CD33.6070406@deriva.de
Whole thread Raw
In response to Re: Performance of full outer join in 8.3  (Grzegorz Jaśkiewicz <gryzman@gmail.com>)
Responses Re: Performance of full outer join in 8.3
Re: Performance of full outer join in 8.3
List pgsql-general
Grzegorz Jaśkiewicz wrote:
> set work_mem=24000; before running the query.
>
> postgres is doing merge and sort on disc, that's always slow.
>
Ok, but why is the plan different in 8.2? As you can see the same query
is really fast in 8.2, but slow in 8.3.
> is there an index on column isin ?
>
There is a separate index on the isin column of the attachment_isins
table (attachment_isins_isin_idx). The other table (rec_isins) has the
combination of attachment and isin as primary key which creates an
implicit index. Can this index be used for the single column isin? And
again: Why doesn't this matter in 8.2??

Regards,
    Christian

--
Deriva GmbH                         Tel.: +49 551 489500-42
Financial IT and Consulting         Fax:  +49 551 489500-91
Hans-Böckler-Straße 2                  http://www.deriva.de
D-37079 Göttingen

Deriva CA Certificate: http://www.deriva.de/deriva-ca.cer


pgsql-general by date:

Previous
From: Grzegorz Jaśkiewicz
Date:
Subject: Re: Performance of full outer join in 8.3
Next
From: Grzegorz Jaśkiewicz
Date:
Subject: Re: Performance of full outer join in 8.3