这个问题没有绝对的解决方案:你要么坚持使用序列功能,要么自己处理。
但是你引起了我的兴趣,我想到了一个(希望不太hacky的)解决方法:创建触发器来完成所有的脏活。
触发器函数
(添加通知以便我们看到发生了什么):
CREATE OR REPLACE FUNCTION update_seq_val_seq_test()
RETURNS TRIGGER AS $$
BEGIN
RAISE NOTICE 'id is %', NEW.id;
IF NEW.id > currval('seq_test_id_seq' :: REGCLASS)
THEN
RAISE NOTICE 'curval is %', currval('seq_test_id_seq' :: REGCLASS);
PERFORM setval('seq_test_id_seq' :: REGCLASS, (NEW.id) :: BIGINT);
RAISE NOTICE 'new curval is %', currval('seq_test_id_seq' :: REGCLASS); END IF;
RETURN NULL;
END;
$$
LANGUAGE 'plpgsql' COST 1;
设置触发器
CREATE TRIGGER seq_test_update_serial
AFTER INSERT ON seq_test
FOR EACH ROW EXECUTE PROCEDURE update_seq_val_seq_test();
扣动扳机
快速而简单的测试
tests2=# insert into seq_test (name) values ('first');
NOTICE: id is 30
INSERT 0 1
tests2=# select * from seq_test;
id | name
----+-------
30 | first
(1 row)
tests2=# select currval('seq_test_id_seq'::regclass);
currval
---------
30
(1 row)
tests2=# insert into seq_test (id, name) values (31, 'thirty one');
NOTICE: id is 31
NOTICE: curval is 30
NOTICE: new curval is 31
INSERT 0 1
tests2=# select currval('seq_test_id_seq'::regclass);
currval
---------
31
(1 row)
tests2=# select * from seq_test;
id | name
----+------------
30 | first
31 | thirty one
(2 rows)
tests2=# insert into seq_test (name) values ('thirty dunno what');
NOTICE: id is 32
INSERT 0 1
tests2=# insert into seq_test (id, name) values (21, 'back to the future');
NOTICE: id is 21
INSERT 0 1
tests2=# select currval('seq_test_id_seq'::regclass);
currval
---------
32
(1 row)
tests2=# select * from seq_test;
id | name
----+--------------------
30 | first
31 | thirty one
32 | thirty dunno what
21 | back to the future
(4 rows)
tests2=# insert into seq_test (name) values ('thirty dunno what++');
NOTICE: id is 33
INSERT 0 1
tests2=# select * from seq_test;
id | name
----+---------------------
30 | first
31 | thirty one
32 | thirty dunno what
21 | back to the future
33 | thirty dunno what++
(5 rows)
现在Postgres处理这种情况更像您想要的方式,但有很多需要检查的事情:它如何处理批量插入、回滚,这个触发器对性能有什么影响,以及其他许多有趣的问题等待您去解决。