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Re: Case-Insensitve Text Comparison

From: Zdenek Kotala <Zdenek(dot)Kotala(at)Sun(dot)COM>
To: "David E(dot) Wheeler" <david(at)kineticode(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Case-Insensitve Text Comparison
Date: 2008-06-03 19:06:48
Message-ID: 48459648.3060706@sun.com (view raw or flat)
Thread:
Lists: pgsql-hackers
David E. Wheeler napsal(a):
> On Jun 3, 2008, at 02:27, Zdenek Kotala wrote:
> 
>> The proposal of GSoc is there:
>> http://archives.postgresql.org/pgsql-hackers/2008-05/msg00857.php
>>
>> It should create basic framework for full SQL COLLATION support. All 
>> comments are welcome.
> 
> That looks great, Zdenek. I'm very excited to have improved SQL 
> COLLATION support in core. But if I could ask a dumb question, how would 
> I specify a case-insensitive collation? Or maybe the Unicode Collation 
> Algorithm is case-insensitive or has case-insensitive support?

It is simple. SQL standard does not specify notation for that (chapter 11.34). 
But there is proposed notation:

CREATE COLLATION <collation name> FOR <character set specification> FROM 
<existing collation name> [ <pad characteristic> ] [ <case sensitive> ] [ 
<accent sensitive> ] [ LC_COLLATE <lc_collate> ] [ LC_CTYPE <lc_ctype> ]

<pad characteristic> := NO PAD | PAD SPACE
<case sensitive> := CASE SENSITIVE | CASE INSENSITIVE
<accent sensitive> := ACCENT SENSITIVE | ACCENT INSENSITIVE


You can specify for each collation if it is case sensitive or not and collation 
function should be responsible to correctly handle this flag.


		Zdenek

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