unordered {} and fn:unordered()

[Martin Probst]

Hi,

> I am wondering whether you have noticed that your favorite XQuery 
> processor indeed realizes such an advantage when it processes 
> expressions of the form unordered {e} or fn:unordered(e)?

X-Hive does. Our native storage doesn't maintain order information on
nodes* because it would inhibit update performance, so ordering can be
quite an expensive operation, so we put quite some effort into
identifying the places where ordering is actually needed. We also cover
all the other places (non-stable order by, max, min, empty ...). 

If you're dealing with lots of nodes and have a path expression that
mixes up order (or that uses a non-document-ordered index), this can
make a significant difference.

Martin