PostgreSQL timestamp踩坑记录与填坑指南
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 "htmlcode">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!
补充:pg查询时间间隔(timestamp类型)
create_date timestamp(6) without time zone1.从2015-10-12到2015-10-13 之间的4点到9点的数据
select * from schedule where create_date between to_date('2015-10-12','yyyy-MM-dd') and to_date('2015-10-13','yyyy-MM-dd') and EXTRACT(hour from create_date) between 4 and 9;结果:
2.2015-10-12五点的数据
select * from schedule where hospital_id='syzyyadmin' and date_trunc('hour',create_date)=to_timestamp('2015-10-12 05','YYYY-MM-DD HH24')结果:
以上为个人经验,希望能给大家一个参考,也希望大家多多支持。如有错误或未考虑完全的地方,望不吝赐教。
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