Re: Patch for collation using ICU - Mailing list pgsql-hackers

From Tatsuo Ishii
Subject Re: Patch for collation using ICU
Date
Msg-id 20050508.220827.104049106.t-ishii@sra.co.jp
Whole thread Raw
In response to Re: Patch for collation using ICU  ("John Hansen" <john@geeknet.com.au>)
List pgsql-hackers
> > I don't buy it. If current conversion tables does the right 
> > thing, why we need to replace. Or if conversion tables are 
> > not correct, why don't you fix it? I think the rule of 
> > character conversion will not change frequently, especially 
> > for LATIN languages. Thus maintaining cost is not too high.
> 
> I never said we need to, but if we're going to implement ICU,
> then we might as well go all the way.

So you admit there's no benefit using ICU for replacing existing
conversions?

Besides ICU does not support all existing conversions, I think ICU has
serious flaw for using conversion. If I understand correctly, ICU uses
UNICODE internally to do the conversion. For example, to implement
SJIS->EUC_JP conversion, ICU first converts SJIS to UNICODE then
converts UNICODE to EUC_JP. Problem is these conversion is not roud
trip(conversion between SJIS/EUC_JP and UNICODE will lose some
information). Thus SJIS->EUC_JP->SJIS conversion using ICU does not
preserve original text.
--
Tatsuo Ishii


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