8.127. subscribeset(p_omit_copy integer, p_sub_forward integer, p_sub_receiver integer, p_sub_provider boolean, p_sub_set boolean)

Function Properties

Language: PLPGSQL

Return Type: bigint

subscribeSet (sub_set, sub_provider, sub_receiver, sub_forward, omit_copy) Makes sure that the receiver is not the provider, then stores the subscription, and publishes the SUBSCRIBE_SET event to other nodes. If omit_copy is true, then no data copy will be done.

declare
	v_set_origin		int4;
	v_ev_seqno			int8;
	v_ev_seqno2			int8;
	v_rec			record;
begin
	-- ----
	-- Grab the central configuration lock
	-- ----
	lock table sl_config_lock;

	--
	-- Check that the receiver exists
	--
	if not exists (select no_id from sl_node where no_id=
	       	      p_sub_receiver) then
		      raise exception 'Slony-I: subscribeSet() receiver % does not exist' , p_sub_receiver;
	end if;

	--
	-- Check that the provider exists
	--
	if not exists (select no_id from sl_node where no_id=
	       	      p_sub_provider) then
		      raise exception 'Slony-I: subscribeSet() provider % does not exist' , p_sub_provider;
	end if;

	-- ----
	-- Check that the origin and provider of the set are remote
	-- ----
	select set_origin into v_set_origin
			from sl_set
			where set_id = p_sub_set;
	if not found then
		raise exception 'Slony-I: subscribeSet(): set % not found', p_sub_set;
	end if;
	if v_set_origin = p_sub_receiver then
		raise exception 
				'Slony-I: subscribeSet(): set origin and receiver cannot be identical';
	end if;
	if p_sub_receiver = p_sub_provider then
		raise exception 
				'Slony-I: subscribeSet(): set provider and receiver cannot be identical';
	end if;
	-- ----
	-- Check that this is called on the origin node
	-- ----
	if v_set_origin != getLocalNodeId('_schemadoc') then
		raise exception 'Slony-I: subscribeSet() must be called on origin';
	end if;

	-- ---
	-- Verify that the provider is either the origin or an active subscriber
	-- Bug report #1362
	-- ---
	if v_set_origin <> p_sub_provider then
		if not exists (select 1 from sl_subscribe
			where sub_set = p_sub_set and 
                              sub_receiver = p_sub_provider and
			      sub_forward and sub_active) then
			raise exception 'Slony-I: subscribeSet(): provider % is not an active forwarding node for replication set %', p_sub_provider, p_sub_set;
		end if;
	end if;

	-- ---
	-- Enforce that all sets from one origin are subscribed
	-- using the same data provider per receiver.
	-- ----
	if not exists (select 1 from sl_subscribe
			where sub_set = p_sub_set and sub_receiver = p_sub_receiver) then
		--
		-- New subscription - error out if we have any other subscription
		-- from that origin with a different data provider.
		--
		for v_rec in select sub_provider from sl_subscribe
				join sl_set on set_id = sub_set
				where set_origin = v_set_origin and sub_receiver = p_sub_receiver
		loop
			if v_rec.sub_provider <> p_sub_provider then
				raise exception 'Slony-I: subscribeSet(): wrong provider % - existing subscription from origin % users provider %',
					p_sub_provider, v_set_origin, v_rec.sub_provider;
			end if;
		end loop;
	else
		--
		-- Existing subscription - in case the data provider changes and
		-- there are other subscriptions, warn here. subscribeSet_int()
		-- will currently change the data provider for those sets as well.
		--
		for v_rec in select set_id, sub_provider from sl_subscribe
				join sl_set on set_id = sub_set
				where set_origin = v_set_origin and sub_receiver = p_sub_receiver
				and set_id <> p_sub_set
		loop
			if v_rec.sub_provider <> p_sub_provider then
				raise exception 'Slony-I: subscribeSet(): also data provider for set % use resubscribe instead',
					v_rec.set_id;
			end if;
		end loop;
	end if;

	-- ----
	-- Create the SUBSCRIBE_SET event
	-- ----
	v_ev_seqno :=  createEvent('_schemadoc', 'SUBSCRIBE_SET', 
			p_sub_set::text, p_sub_provider::text, p_sub_receiver::text, 
			case p_sub_forward when true then 't' else 'f' end,
			case p_omit_copy when true then 't' else 'f' end
                        );

	-- ----
	-- Call the internal procedure to store the subscription
	-- ----
	v_ev_seqno2:=subscribeSet_int(p_sub_set, p_sub_provider,
			p_sub_receiver, p_sub_forward, p_omit_copy);
	
	if v_ev_seqno2 is not null then
	   v_ev_seqno:=v_ev_seqno2;
	 end if;

	return v_ev_seqno;
end;