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MySQL性能指标
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最近在魔改MySQL性能收集器 mysqld-exporter ,接触到一些MySQL常见的性能指标,好好地记录下来学习学习:
SHOW GLOBAL STATUS
中:
-
Slow_queries
是慢查询的数量。具体的慢查询,还需要开慢查询日志( https://dev.mysql.com/doc/refman/5.7/en/slow-query-log.html):
mysql [email protected]:(none)> show variables like '%slow_query_log%'; +---------------------+--------------------------------+ | Variable_name | Value | +---------------------+--------------------------------+ | slow_query_log | OFF | | slow_query_log_file | /var/lib/mysql/ubuntu-slow.log | +---------------------+--------------------------------+ 2 rows in set Time: 0.017s
-
Innodb_row_lock_current_waits
是InnoDB当前被等待的行锁的数量 -
Threads_connected
和Threads_created
是当前打开的线程数和总共创建的线程数 -
Questions
是总共执行的语句数 -
Connections
是总共的连接数 -
Com_select
,Com_insert
,Com_update
,Com_delete
,Com_replace
则是分别对应SELECT
,INSERT
,UPDATE
,DELETE
,REPLACE
语句的数量 -
Qcache_hits
是缓存命中量 -
Select_full_join
是全表连接的数量
SHOW VARIABLES\G
中:
-
max_connections
是最大连接数
SHOW SLAVE STATUS\G
中:
-
Seconds_Behind_Master
是主从之间的延时
当然了,这些指标其实文档上全都有,但是很久不读文档,或者没有DBA那么熟悉文档的话,这样记录一下就还是有用的。
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