Re: UTF8 national character data type support WIP patch and list of open issues.
От | MauMau |
---|---|
Тема | Re: UTF8 national character data type support WIP patch and list of open issues. |
Дата | |
Msg-id | 37B76474BB3149FD841373E12E355851@maumau обсуждение исходный текст |
Ответ на | Re: UTF8 national character data type support WIP patch and list of open issues. (Robert Haas <robertmhaas@gmail.com>) |
Ответы |
Re: UTF8 national character data type support WIP patch and
list of open issues.
Re: UTF8 national character data type support WIP patch and list of open issues. |
Список | pgsql-hackers |
From: "Robert Haas" <robertmhaas@gmail.com> > That may be what's important to you, but it's not what's important to > me. National character types support may be important to some potential users of PostgreSQL and the popularity of PostgreSQL, not me. That's why national character support is listed in the PostgreSQL TODO wiki. We might be losing potential users just because their selection criteria includes national character support. > I am not keen to introduce support for nchar and nvarchar as > differently-named types with identical semantics. Similar examples already exist: - varchar and text: the only difference is the existence of explicit length limit - numeric and decimal - int and int4, smallint and int2, bigint and int8 - real/double precison and float In addition, the SQL standard itself admits: "The <key word>s NATIONAL CHARACTER are used to specify the character type with an implementation- defined character set. Special syntax (N'string') is provided for representing literals in that character set. ... "NATIONAL CHARACTER" is equivalent to the corresponding <character string type> with a specification of "CHARACTER SET CSN", where "CSN" is an implementation-defined <character set name>." "A <national character string literal> is equivalent to a <character string literal> with the "N" replaced by "<introducer><character set specification>", where "<character set specification>" is an implementation- defined <character set name>." > And I think it's an > even worse idea to introduce them now, making them work one way, and > then later change the behavior in a backward-incompatible fashion. I understand your feeling. The concern about incompatibility can be eliminated by thinking the following way. How about this? - NCHAR can be used with any database encoding. - At first, NCHAR is exactly the same as CHAR. That is, "implementation-defined character set" described in the SQL standard is the database character set. - In the future, the character set for NCHAR can be selected at database creation like Oracle's CREATE DATABAWSE .... NATIONAL CHARACTER SET AL16UTF16. The default it the database set. Could you tell me what kind of specification we should implement if we officially support national character types? Regards MauMau
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