作者：张伟
爱可生北京分公司 DBA 团队成员，负责 MySQL 日常问题处理和 DMP 产品维护。喜爱技术和开源数据库，喜爱运动、读书、电影，花草树木。
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pt-query-digest 简介
子曰：“工欲善其事，必先利其器”
善于利用好的性能分析工具可以使运维效率事半功倍。 pt-query-digest 属于 Percona Toolkit 工具集中较为常用的工具，用于分析 slow log，可以分析MySQL数据库的 binary log 、 general log 日志，同时也可以使用 show processlist 或从tcpdump 抓取的 MySQL 协议数据来进行分析。
部署 Percona Toolkit
下载最新版本的 Percona Toolkit
[root@xxx ~]# wget https://www.percona.com/downloads/percona-toolkit/3.2.1/binary/redhat/7/x86_64/percona-toolkit-3.2.1-1.el7.x86_64.rpm
--2020-09-02 06:44:43-- https://www.percona.com/downloads/percona-toolkit/3.2.1/binary/redhat/7/x86_64/percona-toolkit-3.2.1-1.el7.x86_64.rpm
Resolving www.percona.com (www.percona.com)... 74.121.199.234
Connecting to www.percona.com (www.percona.com)|74.121.199.234|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 17397876 (17M) [application/x-redhat-package-manager]
Saving to: ‘percona-toolkit-3.2.1-1.el7.x86_64.rpm’
100%[=====================================================================================================================================================>] 17,397,876 68.3KB/s in 2m 37s
2020-09-02 06:47:27 (108 KB/s) - ‘percona-toolkit-3.2.1-1.el7.x86_64.rpm’ saved [17397876/17397876]
[root@xxx ~]# ls | grep percona-toolkit-3.2.1-1.el7.x86_64.rpm
percona-toolkit-3.2.1-1.el7.x86_64.rpm
PT 工具是使用Perl语言编写和执行的，所以需要系统中有Perl环境。安装相关的依赖包，
[root@xxx ~]# yum install perl-DBI.x86_64
[root@xxx ~]# yum install perl-DBD-MySQL.x86_64
[root@xxx ~]# yum install perl-IO-Socket-SSL.noarch
[root@xxx ~]# yum install perl-Digest-MD5.x86_64
[root@xxx ~]# yum install perl-TermReadKey.x86_64
安装 Percona Toolkit
[root@xxx ~]# rpm -iv percona-toolkit-3.2.1-1.el7.x86_64.rpm
warning: percona-toolkit-3.2.1-1.el7.x86_64.rpm: Header V4 RSA/SHA256 Signature, key ID 8507efa5: NOKEY
Preparing packages...
percona-toolkit-3.2.1-1.el7.x86_64
[root@xxx ~]# rpm -qa | grep percona
percona-toolkit-3.2.1-1.el7.x86_64
工具目录安装路径：/usr/bin
检查慢日志的相关配置
mysql> show variables like '%slow%';
+---------------------------+-------------------------------------+
| Variable_name | Value |
+---------------------------+-------------------------------------+
| log_slow_admin_statements | ON |
| log_slow_slave_statements | ON |
| slow_launch_time | 2 |
| slow_query_log | ON |
| slow_query_log_file | /opt/mysql/data/7777/mysql-slow.log |
+---------------------------+-------------------------------------+
5 rows in set (0.01 sec)
mysql> show variables like 'long_query_time';
+-----------------+----------+
| Variable_name | Value |
+-----------------+----------+
| long_query_time | 1.000000 |
+-----------------+----------+
1 row in set (0.01 sec)
由于更好测试慢日志文件的输出，此处将慢日志执行时间阈值调小。
mysql> set global long_query_time=0.001000;
Query OK, 0 rows affected (0.00 sec)
mysql> show variables like 'long_query_time';
+-----------------+----------+
| Variable_name | Value |
+-----------------+----------+
| long_query_time | 0.001000 |
+-----------------+----------+
1 row in set (0.00 sec)
pt-query-digest 分析慢日志
[root@xxx 7777]# pt-query-digest mysql-slow.log
# 3.6s user time, 100ms system time, 32.64M rss, 227.52M vsz
# Current date: Wed Sep 2 11:22:34 2020
# Hostname: xxx
# Files: mysql-slow.log
# Overall: 37.46k total, 17 unique, 576.26 QPS, 5.58x concurrency ________
# Time range: 2020-09-02T11:21:24 to 2020-09-02T11:22:29
# Attribute total min max avg 95% stddev median
# ============ ======= ======= ======= ======= ======= ======= =======
# Exec time 363s 1ms 183ms 10ms 23ms 8ms 8ms
# Lock time 1s 0 34ms 35us 38us 603us 0
# Rows sent 182.14k 0 100 4.98 0.99 21.06 0
# Rows examine 491.83k 0 1.02k 13.45 97.36 56.85 0
# Query size 19.82M 5 511.96k 554.80 72.65 16.25k 5.75
# Profile
# Rank Query ID Response time Calls R/Call V/M Ite
# ==== ============================= ============== ===== ====== ===== ===
# 1 0xFFFCA4D67EA0A788813031B8... 328.2315 90.4% 30520 0.0108 0.01 COMMIT
# 2 0xB2249CB854EE3C2AD30AD7E3... 8.0186 2.2% 1208 0.0066 0.01 UPDATE sbtest?
# 3 0xE81D0B3DB4FB31BC558CAEF5... 6.6346 1.8% 1639 0.0040 0.01 SELECT sbtest?
# 4 0xDDBF88031795EC65EAB8A8A8... 5.5093 1.5% 756 0.0073 0.02 DELETE sbtest?
# MISC 0xMISC 14.6011 4.0% 3334 0.0044 0.0 <13 ITEMS>
# Query 1: 1.02k QPS, 10.94x concurrency, ID 0xFFFCA4D67EA0A788813031B8BBC3B329 at byte 26111916
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.01
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:29
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 81 30520
# Exec time 90 328s 1ms 129ms 11ms 23ms 8ms 9ms
# Lock time 0 0 0 0 0 0 0 0
# Rows sent 0 0 0 0 0 0 0 0
# Rows examine 0 0 0 0 0 0 0 0
# Query size 0 178.83k 6 6 6 6 0 6
# String:
# Databases test
# Hosts 10.186.60.147
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms ###########################################################
# 100ms #
# 1s
# 10s+
COMMIT\G
# Query 2: 41.66 QPS, 0.28x concurrency, ID 0xB2249CB854EE3C2AD30AD7E3079ABCE7 at byte 24161590
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.01
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:28
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 3 1208
# Exec time 2 8s 1ms 115ms 7ms 24ms 9ms 3ms
# Lock time 38 518ms 17us 34ms 428us 73us 2ms 36us
# Rows sent 0 0 0 0 0 0 0 0
# Rows examine 0 1.18k 1 1 1 1 0 1
# Query size 0 46.01k 39 39 39 39 0 39
# String:
# Databases test
# Hosts 10.186.60.147
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms ##############
# 100ms #
# 1s
# 10s+
# Tables
# SHOW TABLE STATUS FROM `test` LIKE 'sbtest1'\G
# SHOW CREATE TABLE `test`.`sbtest1`\G
UPDATE sbtest1 SET k=k+1 WHERE id=50313\G
# Converted for EXPLAIN
# EXPLAIN /*!50100 PARTITIONS*/
select k=k+1 from sbtest1 where id=50313\G
# Query 3: 56.52 QPS, 0.23x concurrency, ID 0xE81D0B3DB4FB31BC558CAEF5F387E929 at byte 22020829
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.01
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:28
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 4 1639
# Exec time 1 7s 1ms 61ms 4ms 14ms 5ms 2ms
# Lock time 3 45ms 11us 958us 27us 44us 30us 23us
# Rows sent 0 1.60k 1 1 1 1 0 1
# Rows examine 0 1.60k 1 1 1 1 0 1
# Query size 0 57.62k 36 36 36 36 0 36
# String:
# Databases test
# Hosts 10.186.60.147
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms ######
# 100ms
# 1s
# 10s+
# Tables
# SHOW TABLE STATUS FROM `test` LIKE 'sbtest1'\G
# SHOW CREATE TABLE `test`.`sbtest1`\G
# EXPLAIN /*!50100 PARTITIONS*/
SELECT c FROM sbtest1 WHERE id=61690\G
# Query 4: 26.07 QPS, 0.19x concurrency, ID 0xDDBF88031795EC65EAB8A8A8BEEFF705 at byte 21045172
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.02
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:28
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 2 756
# Exec time 1 6s 1ms 104ms 7ms 26ms 10ms 3ms
# Lock time 18 252ms 13us 19ms 333us 54us 2ms 26us
# Rows sent 0 0 0 0 0 0 0 0
# Rows examine 0 756 1 1 1 1 0 1
# Query size 0 25.10k 34 34 34 34 0 34
# String:
# Databases test
# Hosts 10.186.60.147
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms #################
# 100ms #
# 1s
# 10s+
# Tables
# SHOW TABLE STATUS FROM `test` LIKE 'sbtest1'\G
# SHOW CREATE TABLE `test`.`sbtest1`\G
DELETE FROM sbtest1 WHERE id=50296\G
# Converted for EXPLAIN
# EXPLAIN /*!50100 PARTITIONS*/
select * from sbtest1 WHERE id=50296\G
分析pt-query-digest输出结果
第一部分：输出结果的总体信息
# 3.6s user time, 100ms system time, 32.64M rss, 227.52M vsz
说明：
执行过程中在用户中所花费的所有时间
执行过程中内核空间中所花费的所有时间
pt-query-digest进程所分配的内存大小
pt-query-digest进程所分配的虚拟内存大小
# Current date: Wed Sep 2 11:22:34 2020
说明：当前日期
# Hostname: xxx
说明：执行pt-query-digest的主机名
# Files: mysql-slow.log
说明：被分析的文件名
# Overall: 37.46k total, 17 unique, 576.26 QPS, 5.58x concurrency ________
说明：语句总数量，唯一语句数量，每秒查询量，查询的并发
# Time range: 2020-09-02T11:21:24 to 2020-09-02T11:22:29
说明：执行过程中日志记录的时间范围
# Attribute total min max avg 95% stddev median
说明：属性 总计 最小值 最大值 平均值 95% 标准差 中位数
# ============ ======= ======= ======= ======= ======= ======= =======
# Exec time 363s 1ms 183ms 10ms 23ms 8ms 8ms
说明：执行时间
# Lock time 1s 0 34ms 35us 38us 603us 0
说明：锁占用时间
# Rows sent 182.14k 0 100 4.98 0.99 21.06 0
说明：发送到客户端的行数
# Rows examine 491.83k 0 1.02k 13.45 97.36 56.85 0
说明：扫描的语句行数
# Query size 19.82M 5 511.96k 554.80 72.65 16.25k 5.75
说明：查询的字符数
第二部分：输出队列组的统计信息
# Profile
说明：简况
# Rank Query ID Response time Calls R/Call V/M Ite
# ==== ============================= ============== ===== ====== ===== ===
# 1 0xFFFCA4D67EA0A788813031B8... 328.2315 90.4% 30520 0.0108 0.01 COMMIT
# 2 0xB2249CB854EE3C2AD30AD7E3... 8.0186 2.2% 1208 0.0066 0.01 UPDATE sbtest?
# 3 0xE81D0B3DB4FB31BC558CAEF5... 6.6346 1.8% 1639 0.0040 0.01 SELECT sbtest?
# 4 0xDDBF88031795EC65EAB8A8A8... 5.5093 1.5% 756 0.0073 0.02 DELETE sbtest?
# MISC 0xMISC 14.6011 4.0% 3334 0.0044 0.0 <13 ITEMS>
第三部分：输出每列查询的详细信息
# Query 1: 1.02k QPS, 10.94x concurrency, ID 0xFFFCA4D67EA0A788813031B8BBC3B329 at byte 26111916
说明：查询队列1：每秒查询量，查询的并发，队列1的ID值，26111916：表示文中偏移量（查看方法在下面‘偏1’中）
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.01
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:29
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 81 30520
# Exec time 90 328s 1ms 129ms 11ms 23ms 8ms 9ms
# Lock time 0 0 0 0 0 0 0 0
# Rows sent 0 0 0 0 0 0 0 0
# Rows examine 0 0 0 0 0 0 0 0
# Query size 0 178.83k 6 6 6 6 0 6
说明：查询的详细说明，在第一部分/第二部分有相关参数说明
# String:
# Databases test
说明：使用的数据库名称
# Hosts 10.186.60.147
说明：使用的主机IP
# Users root
说明：使用的用户名
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms ###########################################################
# 100ms #
# 1s
# 10s+
说明：查询时间分布
COMMIT\G
说明：执行的慢语句信息
# Query 2: 41.66 QPS, 0.28x concurrency, ID 0xB2249CB854EE3C2AD30AD7E3079ABCE7 at byte 24161590
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.01
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:28
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 3 1208
# Exec time 2 8s 1ms 115ms 7ms 24ms 9ms 3ms
# Lock time 38 518ms 17us 34ms 428us 73us 2ms 36us
# Rows sent 0 0 0 0 0 0 0 0
# Rows examine 0 1.18k 1 1 1 1 0 1
# Query size 0 46.01k 39 39 39 39 0 39
# String:
# Databases test
# Hosts 10.186.60.147
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms ##############
# 100ms #
# 1s
# 10s+
# Tables
# SHOW TABLE STATUS FROM `test` LIKE 'sbtest1'\G
# SHOW CREATE TABLE `test`.`sbtest1`\G
UPDATE sbtest1 SET k=k+1 WHERE id=50313\G
# Converted for EXPLAIN
# EXPLAIN /*!50100 PARTITIONS*/
select k=k+1 from sbtest1 where id=50313\G
# Query 3: 56.52 QPS, 0.23x concurrency, ID 0xE81D0B3DB4FB31BC558CAEF5F387E929 at byte 22020829
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.01
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:28
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 4 1639
# Exec time 1 7s 1ms 61ms 4ms 14ms 5ms 2ms
# Lock time 3 45ms 11us 958us 27us 44us 30us 23us
# Rows sent 0 1.60k 1 1 1 1 0 1
# Rows examine 0 1.60k 1 1 1 1 0 1
# Query size 0 57.62k 36 36 36 36 0 36
# String:
# Databases test
# Hosts 10.186.60.147
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms ######
# 100ms
# 1s
# 10s+
# Tables
# SHOW TABLE STATUS FROM `test` LIKE 'sbtest1'\G
# SHOW CREATE TABLE `test`.`sbtest1`\G
# EXPLAIN /*!50100 PARTITIONS*/
SELECT c FROM sbtest1 WHERE id=61690\G
# Query 4: 26.07 QPS, 0.19x concurrency, ID 0xDDBF88031795EC65EAB8A8A8BEEFF705 at byte 21045172
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.02
# Time range: 2020-09-02T11:21:59 to 2020-09-02T11:22:28
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 2 756
# Exec time 1 6s 1ms 104ms 7ms 26ms 10ms 3ms
# Lock time 18 252ms 13us 19ms 333us 54us 2ms 26us
# Rows sent 0 0 0 0 0 0 0 0
# Rows examine 0 756 1 1 1 1 0 1
# Query size 0 25.10k 34 34 34 34 0 34
# String:
# Databases test
# Hosts 10.186.60.147
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms ################################################################
# 10ms #################
# 100ms #
# 1s
# 10s+
# Tables
# SHOW TABLE STATUS FROM `test` LIKE 'sbtest1'\G
# SHOW CREATE TABLE `test`.`sbtest1`\G
DELETE FROM sbtest1 WHERE id=50296\G
# Converted for EXPLAIN
# EXPLAIN /*!50100 PARTITIONS*/
select * from sbtest1 WHERE id=50296\G
偏1：
可以利用偏移量在慢查询日志文件中到查找到具体的SQL语句，查找方法如下：
[root@xxx 7777]# tail -c +26111916 ./mysql-slow.log | head
# Time: 2020-09-02T11:22:21.062995-00:00
# User@Host: root[root] @ [10.186.60.147] Id: 1177
# Query_time: 0.128524 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0
SET timestamp=1599045741;
COMMIT;
# Time: 2020-09-02T11:22:21.063202-00:00
# User@Host: root[root] @ [10.186.60.147] Id: 1179
# Query_time: 0.126925 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0
SET timestamp=1599045741;
COMMIT;
在生产环境中，可根据输出的慢SQL详情进行合理的语句调整。
参考文档
- https://www.percona.com/doc/percona-toolkit/LATEST/pt-query-digest.html
- https://dev.mysql.com/doc/refman/5.7/en/slow-query-log.html
小女不才，如有不足欢迎指正，告辞。