mysql 系统优化常用sql（1、事务、锁、线程）

-- 查询执行时间最长的sql
select * from information_schema.processlist where Command<>'Sleep' order by
time desc ;

-- 查看当前的事务
SELECT * FROM INFORMATION_SCHEMA.INNODB_TRX;

-- 查看当前锁定的事务

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCKS;

-- 查看当前等锁的事务
SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS;

-- 查询超过5s未提交的事务
SELECT trx_mysql_thread_id AS PROCESSLIST_ID,
       NOW(),
       TRX_STARTED,
       TO_SECONDS(now())-TO_SECONDS(trx_started) AS TRX_LAST_TIME ,
       USER,
       HOST,
       DB,
       TRX_QUERY
FROM INFORMATION_SCHEMA.INNODB_TRX trx
JOIN INFORMATION_SCHEMA.processlist pcl ON trx.trx_mysql_thread_id=pcl.id
WHERE trx_mysql_thread_id != connection_id()
  AND TO_SECONDS(now())-TO_SECONDS(trx_started) >= 5 ;
    
    
--     查看锁等待相关的阻塞线程、被阻塞线程信息及相关用户、IP、PORT
SELECT locked_table,
       locked_index,
       locked_type,
       blocking_pid,
       concat(T2.USER,'@',T2.HOST) AS "blocking(user@ip:port)",
       blocking_lock_mode,
       blocking_trx_rows_modified,
       waiting_pid,
       concat(T3.USER,'@',T3.HOST) AS "waiting(user@ip:port)",
       waiting_lock_mode,
       waiting_trx_rows_modified,
       wait_age_secs,
       waiting_query
FROM sys.x$innodb_lock_waits T1
LEFT JOIN INFORMATION_SCHEMA.processlist T2 ON T1.blocking_pid=T2.ID
LEFT JOIN INFORMATION_SCHEMA.processlist T3 ON T3.ID=T1.waiting_pid;
 

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