This produces no results:
query=auth.accessible_query('read', db.upost)
rows = db(query).select(db.upost.ALL)
but this does produce the desired result:
query=(((db.auth_permission.group_id==auth.user_group(auth.user_id)) & (
db.auth_permission.name=='read') & (db.auth_permission.table_name=='db.upost'))
rows = db(query).select(db.upost.ALL,distinct=
db.upost.id)