> > Second, the
> > default charset for char and varchar might be implemenation dependent,
> > not neccesarily limited to SQL_TEXT. The only requirement is the
> > charset must contain the repertoire SQL_TEXT has. I think any charsets
> > including ascii I've ever seen satisfies the requirement.
>
> Yow! I certainly misremembered the definition. Date and Darwen, 1997,
> point out that the SQL implementation *must* support at least one
> character set, SQL_TEXT, whose repertoire must contain:
>
> 1) Every character that is used in the SQL language itself (this is
> the part I remembered), and
>
> 2) Every character that is included in *any other character set*
> supported by the SQL implementation (Postgres).
>
> This second requirement is presumably to enable text handling of
> multiple character sets, but would seem to put severe restrictions on
> how we would implement things. Or can it act only as a placeholder,
> allowing us to define new character sets as different types in
> Postgres? Otherwise, we would have to retrofit capabilities into
> SQL_TEXT anytime we defined a new character set??
I don't think so. 2) can be read as:
Any other character set must contain every character included in
SQL_TEXT.
This seems extremely easy to implement. We could define SQL_TEXT be a
subset of ASCII and almost any character set contains ASCII chars. As
a result, any character set satisfies above that is logically same as
2). No?
> > Third, the
> > standards says nothing about locale.
>
> You are referring to the Unix-style system support for "locale"?
Yes.
> Certainly the NCHAR and character set support in SQL92 would qualify
> as locale support in the generic sense...
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Tatsuo Ishii