On 3/12/18 08:18, Thomas Kellerer wrote:
> I am not sure if this qualifies as a bug:
>
> query_to_xml() returns an empty XML document when the query returns no rows, e.g:
>
> select query_to_xml('select 42 where false', false, true, '');
>
> The problem with this is, that if the resulting XML is then fed into e.g. the xpath() function, that function fails because the "empty" document is an invalid XML:
That's because you have the tableforest argument set to true. If you
want a proper XML document, then you should write
select query_to_xml('select 42 where false', false, false, '');
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
