no zuo no die系列，来自于pg的wiki。 这一节的内容是：不要使用timestamptz(0)。 理由是: >Because it rounds off the fractional part rather than truncating it as everyone would expect. This can cause unexpected issues; consider that when you store now() into such a column, you might be storing a value half a second in the future. 原因是： 这样的定义会把小数部分舍入而不是大多数所期望的截断。 ``` [local]:5432 pg12@testdb=# drop table if exists t_timestamp1; NOTICE: table "t_timestamp1" does not exist, skipping DROP TABLE Time: 37.935 ms [local]:5432 pg12@testdb=# create table t_timestamp1(id int,time1 timestamptz(0),time2 timestamp); CREATE TABLE Time: 140.401 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# insert into t_timestamp1 values(1,CURRENT_TIMESTAMP,CURRENT_TIMESTAMP); INSERT 0 1 Time: 44.471 ms [local]:5432 pg12@testdb=# insert into t_timestamp1 values(2,now(),now()); INSERT 0 1 Time: 12.053 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# select * from t_timestamp1; id | time1 | time2 ----+------------------------+---------------------------- 1 | 2019-10-22 10:54:13+08 | 2019-10-22 10:54:12.986034 2 | 2019-10-22 10:54:13+08 | 2019-10-22 10:54:13.032517 (2 rows) Time: 3.258 ms [local]:5432 pg12@testdb=# ``` 如案例所示，2019-10-22 10:54:12.986034会被舍入为2019-10-22 10:54:13+08，而不是2019-10-22 10:54:12+08。 **参考资料** [Don't Do This](https://wiki.postgresql.org/wiki/Don't_Do_This)