項(xiàng)目Timezone情況

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()
})

不同時(shí)區(qū)to_timestamp查詢結(jié)果

測試輸入數(shù)據(jù)為1514736000(UTC時(shí)間2017-12-31 16:00:00,北京時(shí)間2018-01-01 00:00:00)

1、timezone=UTC

BEGIN;
SET TIME ZONE 'UTC';
SELECT to_timestamp(1514736000) as datetime;
END;

直接查詢：2017-12-31 16:00:00+00YES

pg查詢:2017-12-31T16:00:00.000ZYES

2、timezone=PRC

BEGIN;
SET TIME ZONE 'PRC';
SELECT to_timestamp(1514736000) as datetime;
END;

直接查詢：2018-01-01 00:00:00+08NO

pg查詢:2017-12-31T16:00:00.000ZYES

PostgreSQL官方文檔對(duì)timestamp的一個(gè)描述

詳見：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進(jìn)行時(shí)間轉(zhuǎn)換且DB時(shí)區(qū)非UTC時(shí)，寫入**timestamp without time zone**類型的COLUMN則會(huì)與預(yù)期結(jié)果不符。

不同Timezone/columnType查詢結(jié)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;

直接查詢：2017-12-31 16:00:00+00YES

pg查詢: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;

直接查詢：2017-12-31 16:00:00YES

pg查詢: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;

直接查詢：2018-01-01 00:00:00+08YES

pg查詢: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;

直接查詢：2017-12-31 16:00:00YES

pg查詢:2017-12-31T08:00:00.000ZNO

據(jù)以上結(jié)果可判定：

使用pg查詢**timestamp without time zone**類型的COLUMN時(shí)，會(huì)將數(shù)據(jù)庫存儲(chǔ)的時(shí)間當(dāng)做北京時(shí)間而非UTC時(shí)間，與數(shù)據(jù)庫時(shí)區(qū)沒有關(guān)系。

總結(jié)

網(wǎng)上類似問題的解決辦法是將DB時(shí)區(qū)改為UTC+08。

原理：寫入DB的時(shí)間實(shí)際為北京時(shí)間，pg庫恰好是當(dāng)做北京時(shí)間讀取，所以時(shí)間戳就不會(huì)出問題了。

假如應(yīng)用部署在不同的地域，使用timestamp without time zone存儲(chǔ)timestamp這樣的設(shè)計(jì)簡直是災(zāi)難。

不要用timestamp without time zone存儲(chǔ)timestamp!

不要用timestamp without time zone存儲(chǔ)timestamp!

不要用timestamp without time zone存儲(chǔ)timestamp!

補(bǔ)充：pg查詢時(shí)間間隔（timestamp類型）

create_date timestamp(6) without time zone

1.從2015-10-12到2015-10-13 之間的4點(diǎn)到9點(diǎn)的數(shù)據(jù)

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;

結(jié)果：

2.2015-10-12五點(diǎn)的數(shù)據(jù)

select * from schedule where hospital_id='syzyyadmin' and date_trunc('hour',create_date)=to_timestamp('2015-10-12 05','YYYY-MM-DD HH24')

結(jié)果：

以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。如有錯(cuò)誤或未考慮完全的地方，望不吝賜教。

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