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  • 高性能MySQL(三):服务器性能剖析

    select * from c LEFT JOIN c100w on c.id=c100w.id;  -- 联合查询
    show PROFILES;  -- 查看查询耗时
    select * from c;
    show PROFILE for  query 1 ;
    
    set @query_id=282;
    select state,sum(DURATION) as total_r,
    ROUND(100*sum(duration)/(select sum(duration) from information_schema.PROFILING 
    where QUERY_ID=@query_id),2) as pct_r,
    count(*) as calls,
    sum(duration)/count(*) as "r/call"
    from information_schema.PROFILING
    where QUERY_ID=@query_id
    GROUP BY STATE
    order by total_r desc
    查询优化
    select * from c LEFT JOIN c100w on c.id=c100w.id;  -- 联合查询
    show PROFILES;  -- 查看查询耗时
    
    select * from c;
    show PROFILE for  query 1 ;
    
    set @query_id=282;
    select state,sum(DURATION) as total_r,
    ROUND(100*sum(duration)/(select sum(duration) from information_schema.PROFILING 
    where QUERY_ID=@query_id),2) as pct_r,
    count(*) as calls,
    sum(duration)/count(*) as "r/call"
    from information_schema.PROFILING
    where QUERY_ID=@query_id
    GROUP BY STATE
    order by total_r desc
    show profile
    flush status;  -- 清除表缓存
    show STATUS where variable_name like 'Handler%' or variable_name like 'Created%'  -- 计数器
    select event_name,count_star,sum_timer_wait 
    from `performance_schema`.events_waits_summary_global_by_event_name
    order by sum_timer_wait desc LIMIT 5
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  • 原文地址:https://www.cnblogs.com/bindot/p/fuwuqxingneng.html
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