Question

需要帮助来优化我的查询，当前它运行大约22秒，并且该表中有110万行。这是我的查询。该查询返回用户的最新时间。

SELECT 
    t.id, t.user_id, t.created
FROM
    timesheets t
WHERE
    t.user_id IN (41649 , 41901,41899,41482,41648,41897,41652,
        41483,41900,41143,41907,16,42191,42195,42194,42136,42193,42190,42484,42485,42486,42504,
        42052,42797,42997,42868,42847,42505,42964)
    AND t.id = (SELECT 
                    MAX(sub_t.id)
                FROM
                    timesheets AS sub_t
                WHERE
                    sub_t.user_id = t.user_id
                AND sub_t.description = 'in')

我也有该表的表索引（id，user_id，创建的，描述）。任何建议都非常感谢。谢谢

Answer 1

多列索引version: '3' services: reverse-proxy: image: traefik command: --api --docker ports: - "8880:80" - "8080:8080" volumes: - /var/run/docker.sock:/var/run/docker.sock whoami: image: containous/whoami labels: - "traefik.frontend.rule=Host:whoami.docker.localhost" - "traefik.frontend.passHostHeader=true"可能会有所帮助。

此外，也许使用联接而不是相关子查询。

(user_id, id)

我假设SELECT t.id, t.user_id, t.created FROM timesheets t JOIN ( SELECT MAX(id) AS maxid FROM timesheets t WHERE user_id IN (41649 , 41901,41899,41482,41648,41897,41652, 41483,41900,41143,41907,16,42191,42195,42194,42136,42193,42190,42484,42485,42486,42504, 42052,42797,42997,42868,42847,42505,42964) AND description = "in" GROUP BY user_id) t1 ON t.id = t1.maxid是表的主键，所以它是唯一索引。

如何优化mysql子查询？

1 个答案: