DECLARE
  v_object_id_one acs_rels.object_id_one%TYPE;
  v_object_id_two acs_rels.object_id_two%TYPE;
  v_rel_type      acs_rels.rel_type%TYPE;
  v_error         text;
  map             record;
BEGIN
  
  -- First check if added this relation violated any relational constraints
  v_error := rel_constraint__violation(new.rel_id);

  if v_error is not null then
      raise EXCEPTION '-20000: %', v_error;
  end if;

  select object_id_one, object_id_two, rel_type
  into v_object_id_one, v_object_id_two, v_rel_type
  from acs_rels
  where rel_id = new.rel_id;

  -- Insert a row for me in group_element_index
  insert into group_element_index
   (group_id, element_id, rel_id, container_id,
    rel_type, ancestor_rel_type)
  values
   (v_object_id_one, v_object_id_two, new.rel_id, v_object_id_one,
    v_rel_type, 'composition_rel');

  -- Add to the denormalized party_approved_member_map

  perform party_approved_member__add(v_object_id_one, member_id, rel_id, rel_type)
  from group_approved_member_map m
  where group_id = v_object_id_two
  and not exists (select 1
          from group_element_map
          where group_id = v_object_id_one
          and element_id = m.member_id
          and rel_id = m.rel_id);

  -- Make my composable elements be elements of my new composite group
  insert into group_element_index
   (group_id, element_id, rel_id, container_id,
    rel_type, ancestor_rel_type)
  select distinct
   v_object_id_one, element_id, rel_id, container_id,
   m.rel_type, ancestor_rel_type
  from group_element_map m
  join acs_rel_types t on (m.rel_type = t.rel_type)
  where group_id = v_object_id_two
  and t.composable_p = 't'
  and not exists (select 1
          from group_element_map
          where group_id = v_object_id_one
          and element_id = m.element_id
          and rel_id = m.rel_id);

  -- For all direct or indirect containers of my new composite group, 
  -- add me and add my elements
  for map in  select distinct group_id
          from group_component_map
          where component_id = v_object_id_one 
  LOOP

    -- Add a row for me

    insert into group_element_index
     (group_id, element_id, rel_id, container_id,
      rel_type, ancestor_rel_type)
    values
     (map.group_id, v_object_id_two, new.rel_id, v_object_id_one,
      v_rel_type, 'composition_rel');

    -- Add to party_approved_member_map

    perform party_approved_member__add(map.group_id, member_id, rel_id, m.rel_type)
    from group_approved_member_map m
    join acs_rel_types t on (m.rel_type = t.rel_type)
    where group_id = v_object_id_two
    and t.composable_p = 't'
    and not exists (select 1
            from group_element_map
            where group_id = map.group_id
            and element_id = m.member_id
            and rel_id = m.rel_id);

    -- Add rows for my composable elements

    insert into group_element_index
     (group_id, element_id, rel_id, container_id,
      rel_type, ancestor_rel_type)
    select distinct
     map.group_id, element_id, rel_id, container_id,
     m.rel_type, ancestor_rel_type
    from group_element_map m
    join acs_rel_types t on (m.rel_type = t.rel_type)
    where group_id = v_object_id_two
    and t.composable_p = 't'
    and not exists (select 1
            from group_element_map
            where group_id = map.group_id
            and element_id = m.element_id
            and rel_id = m.rel_id);
  end loop;

  return new;

END;