sort desc and out of memory exception

[xu cheng]

hi all:
 I configure a solr application and there is a field of type text,and some
kind like this 123456, that is a string of number
and I wanna solr to sort the result on this field
however, when I use sort asc , it works perfectly ,and when I sort it with
desc, the application became unacceptablly slow
and finally , an OutOfMemoryException was throw.
does anyone have the same kind of problem?or any suggestions?

thanks