From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
---|---|
To: | Zdenek Kotala <Zdenek(dot)Kotala(at)Sun(dot)COM> |
Cc: | Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Radek Strnad <radek(dot)strnad(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: [WIP] collation support revisited (phase 1) |
Date: | 2008-07-24 06:32:35 |
Message-ID: | 20080724063235.GA3152@svana.org |
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Lists: | pgsql-hackers |
On Tue, Jul 22, 2008 at 04:32:39PM +0200, Zdenek Kotala wrote:
> >Oh, so you're thinking of a charset as a sort of check constraint. If
> >your locale is turkish and you have a column marked charset ASCII then
> >storing lower('HI') results in an error.
>
> Yeah, if you use strcoll function it fails when illegal character is found.
> See
> http://www.opengroup.org/onlinepubs/009695399/functions/strcoll.html
Wierd, at least in glibc and ICU it can't happen but perhaps there are
other implementations where it can...
> Collation cannot be defined on any character. There is not any relation
> between
> Latin and Chines characters. Collation has sense when you are able to
> specify < = > operators.
There is no standardised relation. However, if your collation library
decides to define all chinese characters after all latin characters,
they will have defined a collation that will work for all strings with
any characters... Which is basically the approach glibc/ICU takes.
I think the standard is kind of pathetic to say that strcoll can set
errno but have no value to indicate error. I wonder how many platforms
actually use that "feature".
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while
> boarding. Thank you for flying nlogn airlines.
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