XMIN/xid vs UNION

Dear all,

some of my views are created with help of the UNION operator.
Now, I also need to include the base table XMIN system column
into those views. Which works fine (as long as I alias them)
except that UNION does an internal sort. My PG version (7.4)
complains about not being able to find a sort operator for
data type XID (of which XMIN is).

Searching the web unearthes a solution for loading those
missing operators for as early as 6.4.1 (1998) !

 http://archives.postgresql.org/pgsql-general/1998-11/msg00096.php

Strangely enough I see those operators listed in the release
notes for 7.2 ...

 http://www.postgresql.org/docs/7.2/interactive/release-7-2.html

Are those operators included in PG > 7.4 ? Should they be ? Is
it my version that's compiled without them, perhaps ?

Thanks,
Karsten
--
GPG key ID E4071346 @ wwwkeys.pgp.net
E167 67FD A291 2BEA 73BD  4537 78B9 A9F9 E407 1346