Fixed hanging during DROP EXTENSION.

Now we SET LOCAL synchronous_commit TO local to avoid hangup.
Also, not used trigger on replica creation code removed.

Author: arssher

bin/shardman_start.sh

@@ -4,7 +4,6 @@ script_dir=`dirname "$(readlink -f "$0")"`
 source "${script_dir}/common.sh"
 
 cd "${script_dir}/.."
-make clean
 
 > $logfile
 
@@ -14,8 +13,10 @@ for port in "${worker_ports[@]}" $master_port; do
     psql -p $port -c "drop extension if exists pg_shardman cascade;"
 done
 
-restart_nodes
+make clean
 make install
+
+restart_nodes
 for port in $master_port "${worker_ports[@]}"; do
     psql -p $port -c "create extension pg_shardman cascade;"
 done

init.sql

@@ -262,6 +262,8 @@ DECLARE
 	sub record;
 	rs record;
 BEGIN
+	RAISE DEBUG '[SHARDMAN %] pg_shardman is dropping, cleaning up', shardman.my_id();
+
 	FOR pub IN SELECT pubname FROM pg_publication WHERE pubname LIKE 'shardman_%' LOOP
 		EXECUTE format('DROP PUBLICATION %I', pub.pubname);
 	END LOOP;
@@ -274,8 +276,10 @@ BEGIN
 		WHERE slot_name LIKE 'shardman_%' AND slot_type = 'logical' LOOP
 		PERFORM shardman.drop_repslot(rs.slot_name, true);
 	END LOOP;
-	-- TODO: remove only shardman's standbys
 	IF shardman.my_id() IS NOT NULL THEN
+		-- otherwise we will hang
+		SET LOCAL synchronous_commit TO local;
+		-- TODO: remove only shardman's standbys
 		PERFORM shardman.set_sync_standbys('');
 	END IF;
 
@@ -285,5 +289,5 @@ $$ LANGUAGE plpgsql;
 CREATE FUNCTION pg_shardman_cleanup_c() RETURNS event_trigger
     AS 'pg_shardman' LANGUAGE C;
 CREATE EVENT TRIGGER cleanup_lr_trigger ON ddl_command_start
-	WHEN TAG in ('DROP EXTENSION')
+	WHEN TAG IN ('DROP EXTENSION')
 	EXECUTE PROCEDURE pg_shardman_cleanup_c();

shard.sql

@@ -287,23 +287,6 @@ BEGIN
 		lname, oldtail_connstr, lname, lname);
 END $$ LANGUAGE plpgsql;
 
--- TODO
--- Update fdw according to new replica creation. We update it on newtail node --
--- its connstring to this part should include only primary and newtail itself,
--- and on all other nodes except oldtail, so they learn about new replica.
--- CREATE FUNCTION replica_created_update_fdw() RETURNS TRIGGER AS $$
--- BEGIN
-	-- RAISE DEBUG '[SHARDMAN] replica_created_update_fdw trigger called';
-	-- IF shardman.my_id() != NEW.prv THEN -- don't update on oldtail node
-		-- PERFORM shardman.update_fdw_server(NEW);
-	-- END IF;
-	-- RETURN NULL;
--- END $$ LANGUAGE plpgsql;
--- CREATE TRIGGER replica_created AFTER INSERT ON shardman.partitions
-	-- FOR EACH ROW WHEN (NEW.prv IS NOT NULL) EXECUTE PROCEDURE replica_created();
--- fire trigger only on worker nodes
--- ALTER TABLE shardman.partitions ENABLE REPLICA TRIGGER replica_created;
-
 -- Otherwise partitioned tables on worker nodes not will be dropped properly,
 -- see pathman's docs.
 ALTER EVENT TRIGGER pathman_ddl_trigger ENABLE ALWAYS;
@@ -656,7 +639,7 @@ BEGIN
 END $$ LANGUAGE plpgsql STRICT;
 
 CREATE FUNCTION get_data_lname(part_name text, pub_node int, sub_node int)
-	RETURNS text AS  'pg_shardman' LANGUAGE C;
+	RETURNS text AS  'pg_shardman' LANGUAGE C STRICT;
 
 -- Make sure that standby_name is present in synchronous_standby_names. If not,
 -- add it via ALTER SYSTEM and SIGHUP postmaster to reread conf.
@@ -667,26 +650,30 @@ BEGIN
 	IF newval IS NOT NULL THEN
 		RAISE DEBUG '[SHARDMAN] Adding standby %, new value is %', standby, newval;
 		PERFORM shardman.set_sync_standbys(newval);
-		PERFORM pg_reload_conf();
 	END IF;
 END $$ LANGUAGE plpgsql STRICT;
 CREATE FUNCTION ensure_sync_standby_c(standby text) RETURNS text
-    AS 'pg_shardman' LANGUAGE C;
+    AS 'pg_shardman' LANGUAGE C STRICT;
 
 -- Remove 'standby' from synchronous_standby_names, if it is there, and SIGHUP
 -- postmaster.
-CREATE FUNCTION remove_sync_standby(standby text) RETURNS void as $$
+CREATE FUNCTION remove_sync_standby(standby text) RETURNS void AS $$
 DECLARE
 	newval text := shardman.remove_sync_standby_c(standby);
 BEGIN
 	IF newval IS NOT NULL THEN
 		RAISE DEBUG '[SHARDMAN] Removing standby %, new value is %', standby, newval;
 		PERFORM shardman.set_sync_standbys(newval);
-		PERFORM pg_reload_conf();
 	END IF;
 END $$ LANGUAGE plpgsql STRICT;
 CREATE FUNCTION remove_sync_standby_c(standby text) RETURNS text
-	AS 'pg_shardman' LANGUAGE C;
+	AS 'pg_shardman' LANGUAGE C STRICT;
 
-CREATE FUNCTION set_sync_standbys(standby text) RETURNS void
-	AS 'pg_shardman' LANGUAGE C;
+CREATE FUNCTION set_sync_standbys(standby text) RETURNS void AS $$
+BEGIN
+	PERFORM pg_reload_conf();
+	PERFORM shardman.set_sync_standbys_c(standby);
+	RAISE DEBUG '[SHARDMAN] sync_standbys set to %', standby;
+END $$ LANGUAGE plpgsql STRICT;
+CREATE FUNCTION set_sync_standbys_c(standby text) RETURNS void
+	AS 'pg_shardman' LANGUAGE C STRICT;

src/udf.c

@@ -402,9 +402,9 @@ remove_sync_standby_c(PG_FUNCTION_ARGS)
  * transaction, so we resort to another exquisite hack: we connect to
  * ourselves via libpq and perform the job.
  */
-PG_FUNCTION_INFO_V1(set_sync_standbys);
+PG_FUNCTION_INFO_V1(set_sync_standbys_c);
 Datum
-set_sync_standbys(PG_FUNCTION_ARGS)
+set_sync_standbys_c(PG_FUNCTION_ARGS)
 {
 	char *standbys = quote_literal_cstr(text_to_cstring(PG_GETARG_TEXT_PP(0)));
 	char *cmd = psprintf("alter system set synchronous_standby_names to %s",