加快ORDER BY查询速度_MySQL
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加快ORDER BY查询速度
想要提高 ORDER BY 的速度，首先要看MySQL能否使用索引而非额外的排序过程。如果不能使用索引，可以试着遵循以下策略：
增加 sort_buffer_size 的值。
增加 read_rnd_buffer_size 的值。
修改 tmpdir，让它指向一个有很多剩余空间的专用文件系统。如果使用MySQL 4.1或更新，这个选项允许有多个路径用循环的格式。
各个路径之间在 Unix 上用冒号（':'）分隔开来，在 Windows，NetWare以及OS/2 上用分号（';'）。
可以利用这个特性将负载平均分摊给几个目录。注意：这些路径必须是分布在不同物理磁盘上的目录，而非在同一个物理磁盘上的不同目录。
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