MySQL优化之Order by 和 Group By 优化

SQL 调优思路

MySQL优化之Order by 和 Group By 优化

查询优化

永远小表驱动大表

MySQL优化之Order by 和 Group By 优化
MySQL优化之Order by 和 Group By 优化

Order by 关键字优化

  • order by子句,尽量使用Index方式排序,避免使用FileSort方式排序
    MySQL优化之Order by 和 Group By 优化
    MySQL优化之Order by 和 Group By 优化
    MySQL优化之Order by 和 Group By 优化

  • 尽可能在索引列上完成排序操作 ,遵照索引建的最佳左前缀

  • 如果不在索引列上,filesort有两种算法:
    mysql就要启动双路排序和单路排序

    双路排序:
    MySQL优化之Order by 和 Group By 优化
    MySQL优化之Order by 和 Group By 优化
    单路排序:
    MySQL优化之Order by 和 Group By 优化
    单路排序的问题:MySQL优化之Order by 和 Group By 优化

  • 优化策略
    MySQL优化之Order by 和 Group By 优化

    MySQL优化之Order by 和 Group By 优化

  • order by 总结
    MySQL优化之Order by 和 Group By 优化

Group by 关键字优化

MySQL优化之Order by 和 Group By 优化