1.74. lockset( integer )

Function Properties

Language: PLPGSQL

Return Type: integer

lockSet(set_id) Add a special trigger to all tables of a set that disables access to it.

declare
	p_set_id			alias for $1;
	v_local_node_id		int4;
	v_set_row			record;
	v_tab_row			record;
begin
	-- ----
	-- Grab the central configuration lock
	-- ----
	lock table sl_config_lock;

	-- ----
	-- Check that the set exists and that we are the origin
	-- and that it is not already locked.
	-- ----
	v_local_node_id := getLocalNodeId('_schemadoc');
	select * into v_set_row from sl_set
			where set_id = p_set_id
			for update;
	if not found then
		raise exception 'Slony-I: set % not found', p_set_id;
	end if;
	if v_set_row.set_origin <> v_local_node_id then
		raise exception 'Slony-I: set % does not originate on local node',
				p_set_id;
	end if;
	if v_set_row.set_locked notnull then
		raise exception 'Slony-I: set % is already locked', p_set_id;
	end if;

	-- ----
	-- Place the lockedSet trigger on all tables in the set.
	-- ----
	for v_tab_row in select T.tab_id,
			slon_quote_brute(PGN.nspname) || '.' ||
			slon_quote_brute(PGC.relname) as tab_fqname
			from sl_table T,
				"pg_catalog".pg_class PGC, "pg_catalog".pg_namespace PGN
			where T.tab_set = p_set_id
				and T.tab_reloid = PGC.oid
				and PGC.relnamespace = PGN.oid
			order by tab_id
	loop
		execute 'create trigger "_schemadoc_lockedset_' || 
				v_tab_row.tab_id || 
				'" before insert or update or delete on ' ||
				v_tab_row.tab_fqname || ' for each row execute procedure
				lockedSet (''_schemadoc'');';
	end loop;

	-- ----
	-- Remember our snapshots xmax as for the set locking
	-- ----
	update sl_set
			set set_locked = getMaxXid()
			where set_id = p_set_id;

	return p_set_id;
end;