From: Lutischán Ferenc <lutischanf@gmail.com>
To: pgsql-performance@postgresql.org
Subject: Improve Seq scan performance
Date: Mon, 10 Nov 2008 07:50:43 +0100
Message-ID: <4917D9C3.9060001@gmail.com> (raw)
Dear List,
I would like to improve seq scan performance. :-)
I have many cols in a table. I use only 1 col for search on it. It is
indexed with btree with text_pattern_ops. The search method is: r like
'%aaa%'
When I make another table with only this col values, the search time is
better when the data is cached. But wronger when the data isn't in cache.
I think the following:
- When there is a big table with many cols, the seq search is read all
cols not only searched.
- If we use an index with full values of a col, it is possible to seq
scan over the index is make better performance (lower io with smaller data).
It is possible to make an index on the table, and make a seq index scan
on this values?
Thanks for helping.
Best Regards,
Ferenc
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: lutischanf@gmail.com
Subject: Re: Improve Seq scan performance
In-Reply-To: <4917D9C3.9060001@gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox