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我正在使用一个大型数据库，我们有一些关键查询依赖 group_concat（通过 myisam）在分组时正确排序多个列。本质上，这样我们才能确保在每一行中获得正确的数据。例如，如果我想知道每个邮政编码中有多少条特定状态的记录，但每个地址只有一条记录：

（id 是唯一的无符号数）

SELECT state     AS state,
       zip       AS zip,
       COUNT(id) AS total
FROM   (SELECT CAST(Substring_index(GROUP_CONCAT(id ORDER BY state, zip, city,
               address,
                      id),
               ',', 1)
               AS UNSIGNED)   AS id,
               CAST(Substring_index(GROUP_CONCAT(zip ORDER BY state, zip, city,
               address
                      , id),
               ',', 1
               ) AS UNSIGNED) AS zip,
               CAST(Substring_index(GROUP_CONCAT(state ORDER BY state, zip, city
               ,
                      address, id),
               ',',
               1) AS CHAR)    AS state
        FROM   DATABASE.table
        GROUP  BY st,
                  zip,
                  city,
                  address) AS a
GROUP  BY zip
ORDER  BY zip

我有一个 myisam 和一个 brighthouse 数据库，其中有相同的数据可供使用。如果我只是做简单的选择，显然brighthouse 具有巨大的性能优势，所以我希望找到一种方法来运行具有相同结果的查询，从而可以利用brighthouse 的速度。

编辑：为了纠正自己，我想找到一个使用 Brighthouse 引擎完成同样事情的查询，而不是我之前所说的 innodb。

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1 回答 1

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我最终发现我可以重新安排一些事情来获得我想要的东西。我原来的问题中的查询可以重写为：

SELECT state     AS state,
       zip       AS zip,
       COUNT(id) AS total
FROM   (SELECT state,
               zip,
               id
        FROM   (SELECT state,
                       zip,
                       id,
                       address
                FROM   DATABASE.table
                ORDER  BY id) AS a
        GROUP  BY address) AS a2
GROUP  BY zip
ORDER  BY zip

...允许相同的结果集并利用 Brighthouse 引擎！:-)

于 2011-07-28T21:17:06.817 回答