begin;
create table smth (
  id serial primary key,
  parent_id int references smth(id) on delete cascade on update cascade,
  data text,
  type_view int not null,
  unique (id, type_view),
  constraint  smth_acrh_cascade_fkey foreign key(parent_id, type_view) references smth(id, type_view) 
        on delete cascade on update cascade deferrable initially deferred
);
create function safe_mode() returns void as $$
BEGIN
        execute 'create rule dont_delete_but_arch AS ON DELETE TO smth DO INSTEAD update smth set type_view = 2 WHERE id = OLD.id';
        RETURN;
END$$ language 'plpgsql';
create function unsafe_mode() returns void as $$
BEGIN
        execute 'drop rule dont_delete_but_arch  ON smth';
        RETURN;
END$$ language 'plpgsql';

insert into smth values ( 0 ,  0 , 'text 1',  1 );
insert into smth values ( 1 ,  0 , 'text 2',  1 );
insert into smth values ( 2 ,  1 , 'text 2.1',  1 );
insert into smth values ( 3 ,  2 , 'text 2.1.1',  1 );
insert into smth values ( 4 ,  2 , 'text 2.1.2',  1 );
select * from smth;
select safe_mode();
delete from smth where id =  2 ;
select * from smth;
select unsafe_mode();
delete from smth where id =  2 ;
select * from smth;
select safe_mode();
delete from smth where id =  1 ;
select * from smth;

rollback;
---- результаты: 

 id | parent_id |    data    | type_view
----+-----------+------------+-----------
   0  |          0  | text  1      |          1 
   1  |          0  | text  2      |          1 
   2  |          1  | text  2 . 1    |          1 
   3  |          2  | text  2 . 1 . 1  |          1 
   4  |          2  | text  2 . 1 . 2  |          1 
(записей:  5 )

 safe_mode
-----------

( 1  запись)

DELETE  0 
 id | parent_id |    data    | type_view
----+-----------+------------+-----------
   0  |          0  | text  1      |          1 
   1  |          0  | text  2      |          1 
   2  |          1  | text  2 . 1    |          2 
   3  |          2  | text  2 . 1 . 1  |          2 
   4  |          2  | text  2 . 1 . 2  |          2 
(записей:  5 )

 unsafe_mode
-------------

( 1  запись)

DELETE  1 
 id | parent_id |  data  | type_view
----+-----------+--------+-----------
   0  |          0  | text  1  |          1 
   1  |          0  | text  2  |          1 
(записей:  2 )

 safe_mode
-----------

( 1  запись)

DELETE  0 
 id | parent_id |  data  | type_view
----+-----------+--------+-----------
   0  |          0  | text  1  |          1 
   1  |          0  | text  2  |          2 
(записей:  2 )