"Andrew Dunstan" <andrew@dunslane.net> wrote
>
> IIRC, Peter Eisentraut noted a while ago that implementing the SQL/XML
> functions properly would require building them into the postgresql parser
> as special cases. That of course would mean we wouldn't be using the
> extension mechanism, and is something we should normally shy away from,
> but I think it could be contemplated for something that is in the
> standard.
>
I guess the reason why SQL/XML should be built into the main parser is the
same as PL/PGSQL. But how did DB2 make it in an extendor way(
http://www-306.ibm.com/software/data/db2/extenders/xmlext/ )? Maybe they
have two copies of SQL parser, one has the basic SQL grammar, the other is
the basic SQL grammar plus or integrated with XML support, once XML extendor
is installed, the basic one will be replaced?
Regards,
Qingqing