libpqxx-2.5.1 has a memory leak that is fixed in 2.5.5 (see http://www.mail-archive.com/libpqxx-general@gborg.postgresql.org/msg00234.html ) libpqxx-2.5.5 has been working ok.
Marking as dupe of 146453 since it's needed for gcc-4.x as well. *** This bug has been marked as a duplicate of 146453 ***