Re: Patch: add conversion from pg_wchar to multibyte

Tatsuo Ishii <ishii@postgresql.org> writes:
>> So far as I can see, the only LCPRVn marker code that is actually in
>> use right now is 0x9d --- there are no instances of 9a, 9b, or 9c
>> that I can find.
>> 
>> I also read in the xemacs internals doc, at
>> http://www.xemacs.org/Documentation/21.5/html/internals_26.html#SEC145
>> that XEmacs thinks the marker code for private single-byte charsets
>> is 0x9e (only) and that for private multi-byte charsets is 0x9f (only);
>> moreover they think 0x9a-0x9d are potential future official multibyte
>> charset codes.  I don't know how we got to the current state of using
>> 0x9a-0x9d as private charset markers, but it seems pretty inconsistent
>> with XEmacs.

> At the time when mule internal code was introduced to PostgreSQL,
> xemacs did not have multi encoding capabilty and mule (a patch to
> emacs) was the only implementation allowed to use multi encoding. So I
> used the specification of mule documented in the URL I wrote.

I see.  Given that upstream has decided that a simpler definition is
more appropriate, is there any reason not to follow their lead, to the
extent that we can do so without breaking existing on-disk data?
        regards, tom lane