PostgreSQL timestamp踩坑记录与填坑指南

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 zone



1.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。