To: K C Lau <kclau60@netvigator.com>
cc: pgsql-performance@postgresql.org
Subject: Re: limitation using LIKE on ANY(array) 
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Comments: In-reply-to K C Lau <kclau60@netvigator.com>
	message dated "Fri, 24 Mar 2006 23:25:00 +0800"
Date: Fri, 24 Mar 2006 11:25:55 -0500
Message-ID: <5275.1143217555@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

K C Lau <kclau60@netvigator.com> writes:
> Indeed, I get rejected even with:
> .. WHERE ANY(array) = 'xx'

> It would only work as documented in the manual (8.10.5):
> SELECT * FROM sal_emp WHERE 10000 = ANY (pay_by_quarter);

That's not changing any time soon; the SQL spec defines only the second
syntax for ANY, and I believe there would be syntactic ambiguity if we
tried to allow the other.

> With 8.1.3, I get an error when trying to do this on a Text[] column :
> .. WHERE ANY(array) LIKE 'xx%'

If you're really intent on doing that, make an operator for "reverse
LIKE" and use it with the ANY on the right-hand side.

regression=# create function rlike(text,text) returns bool as
regression-# 'select $2 like $1' language sql strict immutable;
CREATE FUNCTION
regression=# create operator ~~~ (procedure = rlike, leftarg = text,
regression(# rightarg = text, commutator = ~~);
CREATE OPERATOR
regression=# select 'xx%' ~~~ any(array['aaa','bbb']);
 ?column?
----------
 f
(1 row)

regression=# select 'xx%' ~~~ any(array['aaa','xxb']);
 ?column?
----------
 t
(1 row)

regression=#

			regards, tom lane