Re: Sorting Problem - Mailing list pgsql-general

I agree with all of that except for one caveat:

    all my reading, and just general off the cuff thinking, says that processing variable width characters
SIGNIFICANTLYslows an application. It seems better to PROCESS fixed width characters (1,2,4 byte), and TRANSMIT
variablewidth characters (avoiding the null problem.) 

Gianni Mariani wrote:

> Dennis Gearon wrote:
>
>> Got a link to that section of the standard, or better yet, to a
>> 'interpreted' version of the standard? :-)
>>
>> Stephan Szabo wrote:
>>
>>> On Wed, 13 Aug 2003, Dennis Gearon wrote:
>>>
>>>
>>>> Dennis Bj?rklund wrote:
>>>>
>>>>
>>>>> In the future we need indexes that depend on the locale (and a lot
>>>>> of other changes).
>>>>>
>>>>
>>>> I agree. I've been looking at the web on this subject a lot lately. I
>>>> am **NOT** a microslop fan, but SQL-SERVER even lets a user define a
>>>> language(maybe encoding) down to the column level!
>>>>
>>>> I've been reading on GNU-C and on languages, encoding, and
>>>> localization.
>>>>
>>>> http://pauillac.inria.fr/~lang/hotlist/free/licence/fsf96/drepper/paper-1.html
>>>>
>>>> http://h21007.www2.hp.com/dspp/tech/tech_TechSingleTipDetailPage_IDX/1,2366,1222,00.html
>>>>
>>>>
>>>>
>>>> There are three basic approaches to doing different langauges in
>>>> computerized text:
>>>>
>>>>    A/ various adaptations of the 8 bit character set, I.E. the
>>>> ISO-8859-x series.
>>>>    B/ wide characters
>>>>    ********This should be how Postgress stores data internally.********
>>>>    C/ Multibyte characters
>>>>    ********This is how Postgress should default to sending data OUT
>>>> of the application,
>>>>            i.e. to the display or the web, or other system
>>>> applications********
>>>
>>>
>>>
>>>
>>> SQL has a system for defining character set specifications,
>>> collations and
>>> such (per column/literal in some cases).  We should probably look at it
>>> before making decisions on how to do things.
>>
>>
>
> I thought UNIX (SCOTM) systems also had a way of being able to define
> collation order.
>
> see:
>    ftp://dkuug.dk/i18n/WG15-collection/locales
>
> for a collection of all ISO standardized locales (the WG15 ISO work
> group's stuff).
>
> Do a "man localedef" on most Linuxen or UNIXen.
>
> As for wide characters vs multibyte, there is no clear winner.  The
> right answer DEPENDS on the situation.
>
> Wide characters on some platforms are 16 bit which means that when you
> do Unicode you'll still have problems with surrogate pairs (meaning that
> it's still multi (wide) char) so you still have all the problems of
> multi-byte encodings.
>
> You could decide to process everything in a PG specific 4 byte wide char
> and do all text in Unicode but the overhead in processing 4 times the
> data is quite significant.  The other option is to store all data in
> utf-8 and have all text code become utf-8 aware.
>
> I have found in practice that the utf-8 option is significantly easier
> to implement, 100% Unicode compliant and the best performer (because of
> reduced memory requirements).
> The Posix API's for locales are not very good for modern day programs,
> I'm not sure where the "mbr*" and the "wcr*" apis are in the
> standardization process but if these are not well supported, you're on
> your own and will need to implement similar functionality from scratch
> and for that matter, the collation functions all operate on a "current"
> locate which is really difficult to work with on multi-locale applications.
>
>
>
>
>
>
>
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