Innodb_log_waits 量：Innodb_log_waits 状态变量直接反应出Innodb Log Buffer 空间不足造成等待的次数。
SHOW STATUS LIKE 'Innodb_log_waits';
该变量值发生的频率将直接影响系统的写入性能，所以当该值达到每秒1 次时就该增加系统参数innodb_log_buffer_size 的值，毕竟这是一个系统共用的缓存，适当增加并不会造成内存不足的问题。
二、性能分析命令详解
SHOW STATUS;
FLUSH STATUS;
查看当前连接数 SHOW STATUS LIKE 'Thread_%';
Thread_cached:被缓存的线程的个数
Thread_running：处于激活状态的线程的个数
Thread_connected：当前连接的线程的个数
Thread_created：总共被创建的线程的个数
Thread cache hits
Thread_connected = SHOW GLOBAL STATUS LIKE Thread_created;
Connections = SHOW GLOBAL STATUS LIKE 'Connections';
TCH=(1 - (Threads_created / Connections)) * 100
查看活动连接内容
SHOW PROCESSLIST;
如果 TCH数小于90%,创建连接耗费了时间,增大Thread_cached数量
QPS （每秒查询处理量）MyISAM 引擎
Questions = SHOW GLOBAL STATUS LIKE 'Questions';
Uptime = SHOW GLOBAL STATUS LIKE 'Uptime';
QPS=Questions/Uptime
TPS（每秒传输的事物处理个数），即服务器每秒处理的事务数，如果是InnoDB会显示，没有InnoDB就不会显示。
Com_commit = SHOW GLOBAL STATUS LIKE 'Com_commit';
Com_rollback = SHOW GLOBAL STATUS LIKE 'Com_rollback';
Uptime = SHOW GLOBAL STATUS LIKE 'Uptime';
TPS=(Com_commit + Com_rollback)/Uptime
QPS 和 TPS值一定要实时监控,如果接近架构搭建时的测试峰值,愿上帝与你同在
Read/Writes Ratio
Qcache_hits = SHOW GLOBAL STATUS LIKE 'Qcache_hits';
Com_select = SHOW GLOBAL STATUS LIKE 'Com_select';
Com_insert = SHOW GLOBAL STATUS LIKE 'Com_insert';
Com_update = SHOW GLOBAL STATUS LIKE 'Com_update';
Com_delete = SHOW GLOBAL STATUS LIKE 'Com_delete';
Com_replace = SHOW GLOBAL STATUS LIKE 'Com_replace';
R/W=(Com_select + Qcache_hits) / (Com_insert + Com_update + Com_delete + Com_replace) * 100
读写比,优化数据库的重要依据,读的多就去优化读,写的多就去优化写
Slow queries per minute
Slow_queries = SHOW GLOBAL STATUS LIKE 'Slow_queries';
Uptime = SHOW GLOBAL STATUS LIKE 'Uptime';
SQPM=Slow_queries / (Uptime/60)
Slow queries /Questions Ratio
Slow_queries = SHOW GLOBAL STATUS LIKE 'Slow_queries';
Questions = SHOW GLOBAL STATUS LIKE 'Questions';
S/Q=Slow_queries/Questions
新版本上线时要着重关注慢查询
Full_join per minute
Select_full_join = SHOW GLOBAL STATUS LIKE 'Select_full_join';
Uptime = SHOW GLOBAL STATUS LIKE 'Uptime';
FJPM=Select_full_join / (Uptime/60)
没有使用索引而造成的full_join,优化索引去吧
Innodb buffer read hits
Innodb_buffer_pool_reads = SHOW GLOBAL STATUS LIKE 'Innodb_buffer_pool_reads';
Innodb_buffer_pool_read_requests = SHOW GLOBAL STATUS LIKE 'Innodb_buffer_pool_read_requests';
IFRH=(1 - Innodb_buffer_pool_reads/Innodb_buffer_pool_read_requests) * 100
InnoDB Buffer命中率 目标 95%-99%;
Table Cache
Open_tables= SHOW GLOBAL STATUS LIKE 'Open_tables';
Opened_tables= SHOW GLOBAL STATUS LIKE 'Opened_tables';
table_cache= SHOW GLOBAL STATUS LIKE 'table_cache';
table_cache应该大于 Open_tables 小于 Opened_tables
Temp tables to Disk ratio
Created_tmp_tables = show global status like 'Created_tmp_tables';
Created_tmp_disk_tables = show global status like 'Created_tmp_disk_tables';
TDR=(Created_tmp_disk_tables/Created_tmp_tables)*100
SHOW GLOBAL STATUS LIKE 'Innodb_row_lock_%';
Innodb_row_lock_current_waits
The number of row locks currently being waited for. Added in MySQL 5.0.3.
Innodb_row_lock_time
The total time spent in acquiring row locks, in milliseconds. Added in MySQL 5.0.3.
Innodb_row_lock_time_avg
The average time to acquire a row lock, in milliseconds. Added in MySQL 5.0.3.
Innodb_row_lock_time_max
The maximum time to acquire a row lock, in milliseconds. Added in MySQL 5.0.3.
Innodb_row_lock_waits
The number of times a row lock had to be waited for. Added in MySQL 5.0.3.