如何批量更新Postgres中5500万条记录的单列 [英] How to Update a single column in postgres in a batch for 55 Million records

问题描述

我想更新postgres表的一列。记录大约有5,500万条，所以我们需要一批10000条记录来更新它。 注意：我们希望更新所有行。但我们不想锁定我们的表。

我正在尝试以下查询-

Update account set name = Some name where id between 1 and 10000

我们如何才能对每10000条记录更新一次循环？

如有任何建议和帮助，我们将不胜感激。

PostgreSQL 10.5

推荐答案

与其一次提交所有更改(或其他答案中建议的5,500万次)，我更愿意尝试按您的建议将更新行拆分成小批，例如10k条记录。在PL/pgSQL中，可以使用关键字BY以给定的步骤迭代集合。因此您可以在anonymous code block中进行批量更新，如下所示：

PostgreSQL 11+

DO $$ 
DECLARE 
  page int := 10000;
  min_id bigint; max_id bigint;
BEGIN
  SELECT max(id),min(id) INTO max_id,min_id FROM account;
  FOR j IN min_id..max_id BY page LOOP 
    UPDATE account SET name = 'your magic goes here'
    WHERE id >= j AND id < j+page;
    COMMIT;            
  END LOOP;
END; $$;

• 您可能需要调整WHERE子句以避免不必要的重叠。

---

测试

具有顺序ID的1051行数据示例：

CREATE TABLE account (id int, name text);
INSERT INTO account VALUES(generate_series(0,1050),'untouched record..');

正在执行匿名代码块...

DO $$ 
DECLARE 
  page int := 100;
  min_id bigint; max_id bigint;
BEGIN
  SELECT max(id),min(id) INTO max_id,min_id FROM account;
  FOR j IN min_id..max_id BY page LOOP 
    UPDATE account SET name = now() ||' -> UPDATED ' || j  || ' to ' || j+page
    WHERE id >= j AND id < j+page;
    RAISE INFO 'committing data from % to % at %', j,j+page,now();
    COMMIT;            
  END LOOP;
END; $$;
    
INFO:  committing data from 0 to 100 at 2021-04-14 17:35:42.059025+02
INFO:  committing data from 100 to 200 at 2021-04-14 17:35:42.070274+02
INFO:  committing data from 200 to 300 at 2021-04-14 17:35:42.07806+02
INFO:  committing data from 300 to 400 at 2021-04-14 17:35:42.087201+02
INFO:  committing data from 400 to 500 at 2021-04-14 17:35:42.096548+02
INFO:  committing data from 500 to 600 at 2021-04-14 17:35:42.105876+02
INFO:  committing data from 600 to 700 at 2021-04-14 17:35:42.114514+02
INFO:  committing data from 700 to 800 at 2021-04-14 17:35:42.121946+02
INFO:  committing data from 800 to 900 at 2021-04-14 17:35:42.12897+02
INFO:  committing data from 900 to 1000 at 2021-04-14 17:35:42.134388+02
INFO:  committing data from 1000 to 1100 at 2021-04-14 17:35:42.13951+02

..您可以成批更新您的行。为了证明我的观点，下面的查询按更新时间对记录进行分组：

SELECT DISTINCT ON (name) name, count(id)
FROM account 
GROUP BY name ORDER BY name;

                         name                         | count 
------------------------------------------------------+-------
 2021-04-14 17:35:42.059025+02 -> UPDATED 0 to 100    |   100
 2021-04-14 17:35:42.070274+02 -> UPDATED 100 to 200  |   100
 2021-04-14 17:35:42.07806+02 -> UPDATED 200 to 300   |   100
 2021-04-14 17:35:42.087201+02 -> UPDATED 300 to 400  |   100
 2021-04-14 17:35:42.096548+02 -> UPDATED 400 to 500  |   100
 2021-04-14 17:35:42.105876+02 -> UPDATED 500 to 600  |   100
 2021-04-14 17:35:42.114514+02 -> UPDATED 600 to 700  |   100
 2021-04-14 17:35:42.121946+02 -> UPDATED 700 to 800  |   100
 2021-04-14 17:35:42.12897+02 -> UPDATED 800 to 900   |   100
 2021-04-14 17:35:42.134388+02 -> UPDATED 900 to 1000 |   100
 2021-04-14 17:35:42.13951+02 -> UPDATED 1000 to 1100 |    51

演示：db<>fiddle

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