在系统资源不足的情况下， MySQL 一条最简单的 id=10 查询平均都要好几秒，还有优化的空间吗？ - V2EX
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ashine

在系统资源不足的情况下， MySQL 一条最简单的 id=10 查询平均都要好几秒，还有优化的空间吗？

  •  1      
  •   ashine Apr 26, 2021 1966 views
    This topic created in 1829 days ago, the information mentioned may be changed or developed.

    相同环境下，用 sqlite 查询只需要十几 ms

  • sqlite
  • MySQL
  • 查询
  • 优化
    6 replies    2021-04-26 14:14:51 +08:00
    0ZXYDDu796nVCFxq
        1
    0ZXYDDu796nVCFxq  
       Apr 26, 2021 via Android
    id 是主键吗？如果不是那有没有索引？
    keepeye
        2
    keepeye  
       Apr 26, 2021
    mysql 负载太高了吧
    ch2
        3
    ch2  
       Apr 26, 2021
    改参数，把 cache 大小调低
    ashine
        4
    ashine  
    OP
       Apr 26, 2021
    是特定的某张表查询会这样，无论是索引不索引的语句都很慢。其他表正常
    xmh51
        5
    xmh51  
       Apr 26, 2021
    看下表的锁状态
    ashine
        6
    ashine  
    OP
       Apr 26, 2021
    感谢 @ch2 的提醒，目前调整了一些参数，尤其是把 key_buffer_size 从 128MB 降低到 8MB，增加 table_open_cache 后查询速度有明显的提升，看起来还有优化的空间
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