开启mysql的慢查询

用命令开启慢查询

set global slow_query_log=ON;
set global long_query_time=1;
set global log_queries_not_using_indexes = 1;

查看是否成功

show variables like “%slow%”;
show variables like ‘log_queries_not_using_indexes’;
show global status like ‘%slow%’;

看看慢查询的记录数

 

 

或者

修改mysql的配置文件my.cnf

long_query_time = 2
log-slow-queries = /usr/local/mysql/mysql-slow.log

 

 

MySQL查询缓存设置

select @@query_cache_type;
show variables like ‘have_query_cache’;
set @@global.query_cache_size=400000000;
select @@global.query_cache_size;
select @@global.query_cache_limit;

 

show global status like ‘QCache%’;
show global status like ‘Com_select’;
Mysql的查询缓存命中率 ≈ qcache_hits / (qcache_hits + com_select)