create table denytest ( val integer);
insert into denytest values (1);
create trigger xdeny after insert or update or delete
on denytest for each row execute procedure londiste.deny_trigger();
insert into denytest values (2);
ERROR:  ('Changes no allowed on this table',)
update denytest set val = 2;
ERROR:  ('Changes no allowed on this table',)
delete from denytest;
ERROR:  ('Changes no allowed on this table',)
select londiste.disable_deny_trigger(true);
 disable_deny_trigger 
----------------------
 t
(1 row)

update denytest set val = 2;
select londiste.disable_deny_trigger(true);
 disable_deny_trigger 
----------------------
 t
(1 row)

update denytest set val = 2;
select londiste.disable_deny_trigger(false);
 disable_deny_trigger 
----------------------
 f
(1 row)

update denytest set val = 2;
ERROR:  ('Changes no allowed on this table',)
select londiste.disable_deny_trigger(false);
 disable_deny_trigger 
----------------------
 f
(1 row)

update denytest set val = 2;
ERROR:  ('Changes no allowed on this table',)