Comparing a string against an XPath result set

Hi,

I'm trying to check whether a given string is part of an
XPath result set. I have encountered some performance prob-
lems in the process, but before I track those down further,
I'd like to see if I've chosen the right path to begin with:

| SELECT * FROM $TABLE
|   WHERE $COLUMN = ANY((xpath($EXPR, xmlparse(DOCUMENT $DOC)))::TEXT[]);

In this case, xpath() returns an array of XML fragments made
of a "pure" text child each. I cannot compare XML fragments
with anything, so the conversion to TEXT[] seems to be the
only way I could check whether $COLUMN is a part of those.
 Is there any other way I could tackle this?

Tim