Re: again, LIKE operator

From: "Andy Samuel" <andysamuel(at)geocities(dot)com>
To: <pgsql-general(at)postgresql(dot)org>
Subject: Re: again, LIKE operator
Date: 2002-01-12 10:40:11
Message-ID: 000d01c19b55$82c37ea0$0200a8c0@edpgm
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Just forget my previous email.

PostgreSQL does not use index on LIKE 'a%' but it will use the index if LIKE 'ab%' or something longer.
So the optimizer thinks it is not good enough if it's only 1 character.
Well done !

Thank you
Andy
----- Original Message -----
From: Andy Samuel
To: pgsql-general(at)postgresql(dot)org
Sent: Saturday, January 12, 2002 11:35 AM
Subject: [GENERAL] again, LIKE operator

Dear All

I've search the archive and manuals and it says I should use C locale in order to enable LIKE to use index.
Postgresql was installed after I set the locale to C. So I'm sure the initdb will use C.
From EXPLAIN I know that :

SELECT * FROM GuestProfile WHERE FirstName LIKE 'a' will use index on FirstName

but

SELECT * FROM GuestProfile WHERE FirstName LIKE 'a%' will not use Index on FirstName

I have 9,999,999 records and it was VACUUM ANALYZE-d.

How do I enforce the optimizer to use the index ?

Thank you in advance
Andy

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