PostgreSQL timestamp踩坑记录
项目Timezone情况
NodeJS：UTC+08
PostgreSQL：UTC+00
timestampTest.js
const { Client } = require('pg')
const client = new Client()
client.connect()
let sql = ``
client.query(sql, (err, res) => {
console.log(err ? err.stack : res.rows[0].datetime)
client.end()
})
不同时区to_timestamp查询结果
测试输入数据为1514736000(UTC时间2017-12-31 16:00:00,北京时间2018-01-01 00:00:00)
1、timezone=UTC
BEGIN;
SET TIME ZONE 'UTC';
SELECT to_timestamp(1514736000) as datetime;
END;
- 直接查询：
2017-12-31 16:00:00+00YES - pg查询:
2017-12-31T16:00:00.000ZYES
2、timezone=PRC
BEGIN;
SET TIME ZONE 'PRC';
SELECT to_timestamp(1514736000) as datetime;
END;
- 直接查询：
2018-01-01 00:00:00+08NO - pg查询:
2017-12-31T16:00:00.000ZYES
PostgreSQL官方文档对timestamp的一个描述
详见：8.5.1.3. Time Stamps
In a literal that has been determined to be timestamp without time zone, PostgreSQL will silently ignore any time zone indication. That is, the resulting value is derived from the date/time fields in the input value, and is not adjusted for time zone.
坑
使用to_timestamp进行时间转换且DB时区非UTC时，写入**timestamp without time zone**类型的COLUMN则会与预期结果不符。
不同Timezone/columnType查询结果
1、 timezone=UTC,timestamp with timezone
BEGIN;
SET TIME ZONE 'UTC';
SELECT TIMESTAMP WITH TIME ZONE '2017-12-31T16:00:00+00' as datetime;
END;
- 直接查询：
2017-12-31 16:00:00+00YES - pg查询:
2017-12-31T16:00:00.000ZYES
2、 timezone=UTC,timestamp without timezone
BEGIN;
SET TIME ZONE 'UTC';
SELECT TIMESTAMP '2017-12-31T16:00:00+00' as datetime;
END;
- 直接查询：
2017-12-31 16:00:00YES - pg查询:
2017-12-31T08:00:00.000ZNO
3、 timezone=PRC,timestamp with timezone
BEGIN;
SET TIME ZONE 'PRC';
SELECT TIMESTAMP WITH TIME ZONE '2017-12-31T16:00:00+00' as datetime;
END;
- 直接查询：
2018-01-01 00:00:00+08YES - pg查询:
2017-12-31T16:00:00.000ZYES
4、 timezone=PRC,timestamp without timezone
BEGIN;
SET TIME ZONE 'PRC';
SELECT TIMESTAMP '2017-12-31T16:00:00+00' as datetime;
END;
- 直接查询：
2017-12-31 16:00:00YES - pg查询:
2017-12-31T08:00:00.000ZNO
据以上结果可判定：
使用pg查询**timestamp without time zone**类型的COLUMN时，会将数据库存储的时间当做北京时间而非UTC时间，与数据库时区没有关系。
总结
网上类似问题的解决办法是将DB时区改为UTC+08。
原理：写入DB的时间实际为北京时间，pg库恰好是当做北京时间读取，所以时间戳就不会出问题了。
假如应用部署在不同的地域，使用timestamp without time zone存储timestamp这样的设计简直是灾难。
不要用timestamp without time zone存储timestamp!
不要用timestamp without time zone存储timestamp!
不要用timestamp without time zone存储timestamp!
来源：oschina
链接：https://my.oschina.net/u/135537/blog/1795868