agora inbox for pgsql-sql@postgresql.org  

help / color / mirror / Atom feed

From: James Cloos <cloos@jhcloos.com>
To: Vik Fearing <vik.fearing@dalibo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: matching column of regexps
Date: Mon, 19 May 2014 01:43:33 -0400
Message-ID: <m3r43q5nmp.fsf@carbon.jhcloos.org> (raw)
In-Reply-To: <537951B6.4070202@dalibo.com>
References: <m3wqdi649f.fsf@carbon.jhcloos.org>
	<537951B6.4070202@dalibo.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-sql>

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



-- 
Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-sql

view thread (3+ messages)

Message-ID: <m3r43q5nmp.fsf@carbon.jhcloos.org>
Permalink:  ../m3r43q5nmp.fsf@carbon.jhcloos.org/
Also on:    postgresql.org/message-id/m3r43q5nmp.fsf@carbon.jhcloos.org

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-sql@postgresql.org
  Cc: cloos@jhcloos.com, vik.fearing@dalibo.com
  Subject: Re: matching column of regexps
  In-Reply-To: <m3r43q5nmp.fsf@carbon.jhcloos.org>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox