Add event trigger to update querystring.

pg_ivm--1.10--1.11.sql

@@ -1 +1,23 @@
 ALTER TABLE pgivm.pg_ivm_immv ADD COLUMN querystring text;
+
+CREATE FUNCTION pgivm.refresh_query_strings()
+RETURNS event_trigger LANGUAGE plpgsql AS
+$$
+DECLARE
+	old_search_path text;
+BEGIN
+	-- Empty search path so that get_immv_def returns a fully-qualified query.
+	SELECT setting INTO old_search_path FROM pg_catalog.pg_settings
+		WHERE name = 'search_path';
+	SET search_path = '';
+
+	UPDATE pgivm.pg_ivm_immv SET querystring = pgivm.get_immv_def(immvrelid);
+
+	-- Reset search path to the original value.
+	EXECUTE format('SET search_path = %s', old_search_path);
+END
+$$;
+
+CREATE EVENT TRIGGER refresh_query_strings
+ON ddl_command_end
+EXECUTE FUNCTION pgivm.refresh_query_strings();