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!
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:
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