postgresql7.1 select tree_id, site_wide_p, acs_permission__permission_p(tree_id, :user_id, 'category_tree_read') as has_read_permission from category_trees t where not exists (select 1 from category_tree_map m where m.object_id = :object_id and m.tree_id = t.tree_id) order by t.tree_id