From: | Scott Marlowe <smarlowe(at)g2switchworks(dot)com> |
---|---|
To: | Ibrahim Tekin <itekin(at)gmail(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: LIKE query on indexes |
Date: | 2006-02-21 16:18:00 |
Message-ID: | 1140538679.5777.3.camel@state.g2switchworks.com |
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Thread: | |
Lists: | pgsql-performance |
On Tue, 2006-02-21 at 09:57, Ibrahim Tekin wrote:
> hi,
> i have btree index on a text type field. i want see rows which starts
> with certain characters on that field. so i write a query like this:
>
> SELECT * FROM mytable WHERE myfield LIKE 'john%'
>
> since this condition is from start of the field, query planner should
> use index to find such elements but explain command shows me it will
> do a sequential scan.
>
> is this lack of a feature or i am wrong somewhere?
This is an artifact of how PostgreSQL handles locales other than ASCII.
If you want such a query to use an index, you need to back up your
database, and re-initdb with --locale=C as an argument. Note that you
then will NOT get locale specific matching and sorting.
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