MAX导致数据库超时

2024-01-12 20:32:52

需求：获取指定用户下某个邮箱最近一次发送时间

场景：

CREATE_TIME已经添加索引

原语句：(max导致全表扫描！！！)

SELECT
    MAX(CREATE_TIME) AS MAX0
FROM
    t_mail_send_extend
WHERE
    USER_ID = ‘03515d6956c0434c86175835b9fae0bf‘
AND LOCATE(
    ‘sebastian.sandoli@ladespensa.es‘,
    ADDRESS
)
AND STATUS = 1

改进：

SELECT
    CREATE_TIME
FROM
    t_mail_send_extend
WHERE
    USER_ID = ‘03515d6956c0434c86175835b9fae0bf‘
 AND LOCATE(
     ‘sebastian.sandoli@ladespensa.es‘,
     ADDRESS
 )
AND STATUS = 1 ORDER BY CREATE_TIME DESC LIMIT 1

MAX导致数据库超时

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