Mysql数据库慢sql抓取与分析

1、修改mysql配置开启慢sql查询

修改配置文件/etc/my.cnf

slow_query_log=ON
slow_query_log_file=/usr/local/mysql/data/slow.log
long_query_time=5

说明：long_query_time这个时间大家可以设置为1，不放过任何超过1秒的查询。 

2、检查设置

show VARIABLES like '%slow_query_log%';
show VARIABLES like '%long_query_time%';

 

 

 3、安装安装pt_query_digest

wget percona.com/get/pt-query-digest
mv pt-query-digest /usr/bin/
chmod +x /usr/bin/pt-query-digest

安装与Perl相关的模块

yum  -y  install 'perl(Data::Dumper)'
yum  -y  install  perl-Digest-MD5
yum  -y  install  perl-DBI
yum  -y  install  perl-DBD-MySQL

4、分析慢sql日志文件

#全部

pt-query-digest slow.log > pt_slow_sql_report.log

#近30天的

pt-query-digest --since=30d mysql.log  > pt_slow_sql_report.rtf

 以下是分析结果截取示例，分析结果文档会给出每个慢sql的详细信息。

# 570.6s user time, 47s system time, 88.15M rss, 252.14M vsz
# Current date: Wed Jun 29 17:33:45 2022
# Hostname: izzm08qanynb5doqrznbeyz
# Files: mysql.log
# Overall: 722.25k total, 212 unique, 0.28 QPS, 2.88x concurrency ________
# Time range: 2022-05-30T17:25:05 to 2022-06-29T09:20:58
# Attribute          total     min     max     avg     95%  stddev  median
# ============     ======= ======= ======= ======= ======= ======= =======
# Exec time        7376702s      5s    122s     10s     24s      7s      7s
# Lock time          3079s       0     56s     4ms   204us   437ms    84us
# Rows sent         15.08M       0  32.56k   21.89    0.99  517.96    0.99
# Rows examine       3.11T       0  32.05M   4.52M   6.94M   2.51M   5.99M
# Query size       542.74M      27   5.86k  787.96   2.27k  907.02  299.03