Re: Proposal: CREATE CONVERSION

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От Tatsuo Ishii
Тема Re: Proposal: CREATE CONVERSION
Дата
Msg-id 20020711.153749.71182832.t-ishii@sra.co.jp
обсуждение исходный текст
Ответ на Re: Proposal: CREATE CONVERSION  (Karel Zak <zakkr@zf.jcu.cz>)
Ответы Re: Proposal: CREATE CONVERSION  (Karel Zak <zakkr@zf.jcu.cz>)
Список pgsql-hackers
> > For example you want to define a function for LATIN1 to UNICODE conversion
> > function would look like:
> > 
> > function_for_LATIN1_to_UTF-8(from_string opaque, to_string opaque, length
> > integer)
> > {
> >     :
> >     :
> >     generic_function_using_iconv(from_str, to_str, "ISO-8859-1", "UTF-8",
> >     length);
> > }
> > 
> > CREATE FUNCTION function_for_LATIN1_to_UTF-8(opaque, opaque, integer)
> > RETURNS integer;
> > CREAE CONVERSION myconversion FOR 'LATIN1' TO 'UNICODE' FROM
> > function_for_LATIN1_to_UTF-8;
> 
>  Hmm, but it require define "function_for_..." for each conversion. 
>  For example trigger function I needn't define for each table, but I can
>  use only one PostgreSQL function for arbirary table.

I don't think this is a big problem, IMO.

However, thinking more, I came to a conclusion that passing encoding
ids would be a good thing. With the encoding id parameters, the
function could check if it is called with correct encodings, and this
would prevent disaster. New interface proposal:
pgconv(    INTEGER,    -- source encoding id    INTEGER,    -- destination encoding id    OPAQUE,        -- source
string(null terminated C string)    OPAQUE,        -- destination string (null terminated C string)    INTERGER    --
sourcestring length) returns INTEGER;    -- dummy. returns nothing, actually.
 

--
Tatsuo Ishii


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