如何将数据从一个表插入/更新到另一个表(postgresql)？

Question

有两张桌子

tmp_stat:
date, site_id, ip, block_id, count
Primary Key (date, site_id, ip, block_id)

main_stat:
date, site_id, ip, block_id, count
Primary Key (date, site_id, ip, block_id)

当没有这样的(date,site_id等)时,我需要从tmp_stat向main_stat插入行,并且当它们已经尽快存在时,需要更新计数

tmp_stat包含大约500000行,main_stat包含millons

Answer 1

以下工作如何？

WITH upd AS (
    UPDATE main_stat t
       SET counter = s.counter
      FROM tmp_stat s
     WHERE t.date = s.date
            AND t.site_id = s.site_id
            AND t.ip = s.ip
            AND t.block_id = s.block_id
 RETURNING s.date, s.site_id, s.ip, s.block_id, s.counter
)
INSERT INTO main_stat
     SELECT s.mydate, s.site_id, s.ip, s.block_id, s.counter
       FROM tmp_stat s 
       LEFT JOIN upd ON (upd.date = s.date and  upd.site_id = s.site_id and upd.ip = s.ip and upd.block_id = s.block_id)
      WHERE upd.date IS NULL
;

更新:

看起来这只适用于9.1或更高版本.

使用just-somebody的建议WHERE (t.date, t.site_id, t.ip, t.block_id) = (s.date, s.site_id, s.ip, s.block_id)似乎可以提供更好的性能.

WITH upd AS (
    UPDATE main_stat t
       SET counter = s.counter
      FROM tmp_stat s
     WHERE ( t.date, t.site_id, t.ip, t.block_id ) = ( s.date, s.site_id, s.ip, s.block_id )
 RETURNING s.date, s.site_id, s.ip, s.block_id
)
INSERT INTO main_stat
     SELECT s.date, s.site_id, s.ip, s.block_id, s.counter
       FROM tmp_stat s 
       LEFT JOIN upd 
            ON ( upd.date = s.date 
                AND upd.site_id = s.site_id 
                AND upd.ip = s.ip 
                AND upd.block_id = s.block_id )
      WHERE upd.date IS NULL
;

这里发生的是我们使用CTE进行UPDATE,CTE返回更新行的标识列.

然后,INSERT使用更新的行信息来过滤tmp_stat以仅插入新记录.

Dimitri Fontaine在本博客文章中介绍了一些并发性警告.

有关CTE的更多信息可以在Postgresql 文档中找到.