> On 16 Jul 2019, at 13:55, PG Bug reporting form <noreply@postgresql.org> wrote:
> --Incorrect, ASCII 'A', 'D', and 'test' > ASCII '2' or UT8 values as well.
> SELECT xpath('/row/c1', xmlrecord) as c1, xpath('/row/c2[@m=2 or not(@m)]',
> t.xmlrecord) as row, xpath('/row/c2[@m=2 or not(@m)]/text() >=
> ''2''',t.xmlrecord) VAL FROM test t;
> -- {<c1>Manual</c1>} | {<c2>1</c2>,"<c2 m=\"2\">2</c2>"} | {true}
> -- {<c1>Apropos</c1>} | {<c2>1</c2>,"<c2 m=\"2\">2</c2>"} | {true}
> -- {<c1>Apropos</c1>} | {<c2>1</c2>,"<c2 m=\"2\">3</c2>"} | {true}
> -- {<c1>Apropos</c1>} | {<c2>1</c2>,"<c2 m=\"2\">A</c2>"} | {false}
> -- {<c1>Apropos</c1>} | {<c2>1</c2>,"<c2 m=\"2\">D</c2>"} | {false}
> -- {<c1>Apropos</c1>} | {<c2>1</c2>,"<c2 m=\"2\">test</c2>"} | {false}
Far from being an exprt in this area, but AFAIK xpath() is evaluated as XPath
1.0 and according to the specification [1] only = and != comparison are defined:
"When neither object to be compared is a node-set and the operator is <=, <,
>= or >, then the objects are compared by converting both objects to
numbers and comparing the numbers according to IEEE 754."
‘A', 'D' and ‘test’ are thus converted to floating point NaN’s.
cheers ./daniel
[1] https://www.w3.org/TR/1999/REC-xpath-19991116/#booleans