Re: PostgreSQL vs SQL/XML Standards

(It would not be exactly overloading, because of the special sugared
syntax known to the parser, but it could look like overloading, and be
intuitive to the user.)

If you have convenient access to Oracle to check compatibility, could you
compare this query?

SELECT * FROM XMLTABLE('.'
PASSING '<sale hatsize="7" customer="alice" taxable="false"/>'
COLUMNS
a boolean PATH 'string("cat" < "dog")',
b boolean PATH 'string("cat" > "dog")',
c boolean PATH 'string(sale/@taxable = false())');

(I suspect in Oracle it would also work without the string() wrappings,
but just to make it easy, I think this way it will work in both Oracle
and PG—that is, not error, though results may differ.)

I have a access to too old 11.2 Oracle.  There I had to modify query because there is not boolean type. I replaced bool by int, but I got a error

ORA-19224:XPTY-004 .. expected node()*, got xs:string - it doesn't work with/without string() wrappings.

Regards

Pavel Stehule