技术分享 | 使用 pt-query-digest 分析慢日志

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    作者：张伟
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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)

    image

    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>

    image

    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

    小女不才，如有不足欢迎指正，告辞。

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