在线路519重新启动序列和truncate table看起来不错,但如果一个rollbacked事务中运行,截断不会发生,但序列重启will
Important: Because sequences are non-transactional, changes made by setval are not undone if the transaction rolls back.
见:
s1=> create table test1 (id serial primary key, a text not null);
CREATE TABLE
s1=> \d
List of relations
Schema | Name | Type | Owner
--------+--------------+----------+--------
public | test1 | table | albert
public | test1_id_seq | sequence | albert
(2 rows)
s1=> insert into test1(a) values ('apple');
INSERT 0 1
s1=> select * from test1;
id | a
----+-------
1 | apple
(1 row)
s1=> select * from test1_id_seq;
sequence_name | last_value | start_value | increment_by | max_value | min_value | cache_value | log_cnt | is_cycled | is_called
---------------+------------+-------------+--------------+---------------------+-----------+-------------+---------+-----------+-----------
test1_id_seq | 1 | 1 | 1 | 9223372036854775807 | 1 | 1 | 32 | f | t
(1 row)
s1=> insert into test1(a) values ('bannana');
INSERT 0 1
s1=> select * from test1;
id | a
----+---------
1 | apple
2 | bannana
(2 rows)
s1=> insert into test1(a) values ('bannana');
INSERT 0 1
s1=> select * from test1;
id | a
----+---------
1 | apple
2 | bannana
3 | bannana
(3 rows)
s1=> select * from test1_id_seq;
sequence_name | last_value | start_value | increment_by | max_value | min_value | cache_value | log_cnt | is_cycled | is_called
---------------+------------+-------------+--------------+---------------------+-----------+-------------+---------+-----------+-----------
test1_id_seq | 3 | 1 | 1 | 9223372036854775807 | 1 | 1 | 30 | f | t
(1 row)
s1=> begin;
BEGIN
s1=> alter sequence test1_id_seq RESTART WITH 1;
ALTER SEQUENCE
s1=> truncate table test1;
TRUNCATE TABLE
s1=> rollback;
ROLLBACK
s1=> select * from test1_id_seq;
sequence_name | last_value | start_value | increment_by | max_value | min_value | cache_value | log_cnt | is_cycled | is_called
---------------+------------+-------------+--------------+---------------------+-----------+-------------+---------+-----------+-----------
test1_id_seq | 1 | 1 | 1 | 9223372036854775807 | 1 | 1 | 0 | f | f
(1 row)
s1=> select * from test1;
id | a
----+---------
1 | apple
2 | bannana
3 | bannana
(3 rows)
s1=>
“TRUNCATE ... RESTART IDENTITY”也是如此。 –
这是一个有趣的笔记。但我不确定它适用于这里的具体失败。隔离测试我仍然失败。这似乎与使用预处理语句有关,因为它们只是运行我们没有使用事务的执行测试。 –