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Message-ID: <4917D9C3.9060001@gmail.com>
Date: Mon, 10 Nov 2008 07:50:43 +0100
From: =?ISO-8859-2?Q?Lutisch=E1n_Ferenc?= <lutischanf@gmail.com>
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To: pgsql-performance@postgresql.org
Subject: Improve Seq scan performance
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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