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Message-ID: <b42b73150704222216l1e56c331tfc8c7daa59a22499@mail.gmail.com>
Date: Mon, 23 Apr 2007 10:46:23 +0530
From: "Merlin Moncure" <mmoncure@gmail.com>
To: chrisj <chrisj.wood@sympatico.ca>
Subject: Re: seeking advise on char vs text or varchar in search table
Cc: pgsql-performance@postgresql.org
In-Reply-To: <10103002.post@talk.nabble.com>
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References: <10103002.post@talk.nabble.com>

On 4/20/07, chrisj <chrisj.wood@sympatico.ca> wrote:
>
> I have a table that contains a column for keywords that I expect to become
> quite large and will be used for web searches.  I will either index the
> column or come up with a simple hashing algorithm add the hash key to the
> table and index that column.
>
> I am thinking the max length in the keyword column I need to support is 30,
> but the average would be less than10
>
> Any suggestions on whether to use char(30), varchar(30) or text, would be
> appreciated.  I am looking for the best performance option, not necessarily
> the most economical on disk.

Don't use char...it pads out the string to the length always.   It
also has no real advantage over varchar in any practical situation.
Think of varchar as text with a maximum length...its no faster or
slower but the database will throw out entries based on length (which
can be good or a bad thing)...in this case, text feels better.

Have you looked at tsearch2, gist, etc?

merlin