From: James Cloos <cloos@jhcloos.com>
To: Vik Fearing <vik.fearing@dalibo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: matching column of regexps
In-Reply-To: <537951B6.4070202@dalibo.com> (Vik Fearing's message of "Sun, 18
 May 2014 20:35:02 -0400")
References: <m3wqdi649f.fsf@carbon.jhcloos.org> <537951B6.4070202@dalibo.com>
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Date: Mon, 19 May 2014 01:43:33 -0400
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>>>>> "VF" == Vik Fearing <vik.fearing@dalibo.com> writes:

JC>> Is there a better way to answer the question, "Do ANY rows match?"

VF> select exists (select 1 from retest where active is true and ? ~ re);

Ah.  Yes.  I'd forgotten about select exists.  I cannot recall whether I
ever used it in anger, or just played around after reading about it.

It should stick this time.

>> Is there a way to index such a table/query?

VF> There are several ways to index such a query.  If there are very many
VF> rows but with only a few being active, then a partial index will do wonders.

Its more likely only a few will be inactive.

VF> Otherwise, it is possible to use an index for regular expressions using
VF> the pg_trgm extension.

Perfect.  I see trgm index support for ~, et alia is new in 9.3.

Exactly the kicks in the skull I needed.

Thanks,

-JimC
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James Cloos <cloos@jhcloos.com>         OpenPGP: 0x997A9F17ED7DAEA6


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