org.postgresql.util.PSQLException: ERROR: could not identify an equality operator for type xml

I have added one column with xml type ,after adding I am getting following error.

org.postgresql.util.PSQLException: ERROR: could not identify an equality operator for type xml

If I have removed column following query works fine

select * from (select * from KM_COURSE_MAST where ID in (select OBJ_ID from  (select  OBJ_ID,PERFORMER_TYPE,PERFORMER_ID from  KM_REL_OBJ_PER_ACTION where OBJ_TYPE='COURSETYPE') g where  PERFORMER_TYPE='GROUP' and PERFORMER_ID in ((WITH RECURSIVE parents as ( select PARENT_ID from KM_REL_SELF_GROUP where CHILD_ID in ( SELECT GROUP_ID FROM KM_REL_GRP_USER WHERE USER_ID=46467) UNION select a.PARENT_ID FROM KM_REL_SELF_GROUP a ,parents p where a.CHILD_ID = p.PARENT_ID ) select PARENT_ID from  parents order by PARENT_ID asc)union SELECT GROUP_ID FROM KM_REL_GRP_USER WHERE USER_ID=46467)) union select * from KM_COURSE_MAST where CREATED_BY='46467') KM_COURSE_MAST   order by DISPLAYORDER

Thanks,

Gajendra