大表查询优化（mysql）

Question

该表包含1.2mill结果，我无法编辑它，因为有些应用程序我没有源代码来访问它。我想添加一个数量字段，但我不能。

这里是我使用的查询：

SELECT SUM(assets.hourlyEarnings) as earnings, 
     assets_inventory.uid 
    FROM (assets) 
    JOIN assets_inventory ON assets.id = assets_inventory.assetID 
    WHERE assets_inventory.uid IN (SELECT users.uid 
            FROM users 
            WHERE users.assetTime < 1305350756) 
GROUP BY uid 

有很多重复的记录。

下面是表：

CREATE TABLE IF NOT EXISTS assets_inventory (
    id int(11) NOT NULL AUTO_INCREMENT, 
    uid bigint(20) NOT NULL, 
    assetID int(11) NOT NULL, 
    PRIMARY KEY (id), 
    KEY uid (uid) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=1231992 ; 

平均而言，我服用6-7秒拉的结果，任何建议加快这将不胜感激！

Answer 1

如果你希望所有uid值的列表，不管是否有相关的收益：

SELECT DISTINCT 
      ai.uid, 
      COALESCE(x.earnings, 0) AS earnings 
    FROM ASSETS_INVENTORY ai 
LEFT JOIN (SELECT t.id, 
        SUM(t.hourlyearnings) AS earnings 
      FROM ASSETS t 
     GROUP BY t.id) x ON x.id = ai.assetid 
    WHERE EXISTS (SELECT NULL 
        FROM USERS u 
        WHERE u.uid = ai.uid 
        AND u.assettime < 1305350756) 

否则：

SELECT ai.uid, 
     SUM(a.hourlyearnings) AS earnings 
    FROM ASSETS_INVENTORY ai 
    JOIN ASSETS a ON a.id = ai.assetid 
    WHERE EXISTS (SELECT NULL 
        FROM USERS u 
        WHERE u.uid = ai.uid 
        AND u.assettime < 1305350756) 
GROUP BY ai.uid 

...或：

SELECT ai.uid, 
     SUM(a.hourlyearnings) AS earnings 
    FROM ASSETS_INVENTORY ai 
    JOIN ASSETS a ON a.id = ai.assetid 
    JOIN USERS u ON u.uid = ai.uid 
       AND u.assettime < 1305350756 
GROUP BY ai.uid