https://gist.github.com/gmcharlt/5568683

Using perl_xpath with your example seems to have the desired effect (though note that the XPath expression should probably be ‘/ns1:testxml/ns1:foo’, not ‘/testxml/ns1:foo’.

SELECT xpath(
‘/foo/bar/text()’,
(xpath(
‘/testxml/ns1:foo’,
‘baz’::xml,
ARRAY[
['ns1','http://www.example.com'],
['ns2','http://www.example2.com']
]
))[1]
);
xpath
——-
{baz}
(1 row)

However, if there are several, you’re screwed unless you want all of them or only a number of them but don’t care which ones:

select xpath(‘/foo/bar/text()’, xml ‘ns1barns2bar’);
xpath
—————–
{ns1bar,ns2bar}
(1 row)

If someone can come up with something better, I’m interested too.