Re: Case-Insensitve Text Comparison

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