From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert DiFalco <robert.difalco@gmail.com>
cc: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Question about trigram GIST index
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Comments: In-reply-to Robert DiFalco <robert.difalco@gmail.com>
 message dated "Thu, 18 Dec 2014 09:12:16 -0800"
Date: Thu, 18 Dec 2014 12:18:52 -0500
Message-ID: <18097.1418923132@sss.pgh.pa.us>
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Robert DiFalco <robert.difalco@gmail.com> writes:
> So, for my use case I simply need to search for a case insensitive
> substring. It need not be super exact. It seems like there are two ways I
> can do this:

> CREATE INDEX idx_users_name ON users USING GIST(lower(name) gist_trgm_ops);
> SELECT * FROM users WHERE lower(name) LIKE '%john%';

> Or I can do it like this:

> CREATE INDEX idx_users_name ON users USING GIST(name gist_trgm_ops);
> SELECT * FROM users WHERE name % 'john';

Hm, I don't see anything in the pg_trgm docs suggesting that % is
case-insensitive.  But in any case, I'd go with the former as being
more understandable to someone who knows standard SQL.

			regards, tom lane


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