9.29. Event Trigger Functions_.pavcwetriggerfunction

9.29 事件触发器函数

PostgreSQL提供用以从事件触发器中获取信息的函数。

 

有关事件触发器的更多信息，请参见第39章。

9.29.1. Capturing Changes at Command End

9.29.1 在命令结束时获取变化

pg_event_trigger_ddl_commands () → setof record

pg_event_trigger_ddl_commands返回由用户调用附加了ddl_command_end事件触发器的函数时执行的DDL命令列表。它返回如下列：

9.29.2. Processing Objects Dropped by a DDL Command

9.29.2 处理使用DDL命令删掉的对象

pg_event_trigger_dropped_objects () → setof record

pg_event_trigger_dropped_objects返回调用了sql_drop事件删除的数据库对象列表。其返回如下列：

示例：

CREATE FUNCTION test_event_trigger_for_drops()
RETURNS event_trigger LANGUAGE plpgsql AS $$
DECLARE
obj record;
BEGIN
FOR obj IN SELECT * FROM pg_event_trigger_dropped_objects()
LOOP
RAISE NOTICE '% dropped object: % %.% %',
tg_tag,
obj.object_type,
obj.schema_name,
obj.object_name,
obj.object_identity;
END LOOP;
END
$$;
CREATE EVENT TRIGGER test_event_trigger_for_drops
ON sql_drop
EXECUTE FUNCTION test_event_trigger_for_drops();

9.29.3. Handling a Table Rewrite Event

9.29.3 表重写事件处理

表9.98提供的函数，用以返回调用table_rewrite事件的相关信息。

示例：

CREATE FUNCTION test_event_trigger_table_rewrite_oid()
RETURNS event_trigger
LANGUAGE plpgsql AS
$$
BEGIN
RAISE NOTICE 'rewriting table % for reason %',
pg_event_trigger_table_rewrite_oid()::regclass,
pg_event_trigger_table_rewrite_reason();
END;
$$;
CREATE EVENT TRIGGER test_table_rewrite_oid
ON table_rewrite
EXECUTE FUNCTION test_event_trigger_table_rewrite_oid();