Example analysis of usage records of pt-query-digest tool in MySQL-Mysql Tutorial-php.cn

This article brings you relevant knowledge about mysql. It mainly introduces a tool pt-query-digest for analyzing mysql slow query logs. Let’s take a look at it together. I hope it will be helpful to everyone.

1. Introduction

pt-query-digest is a tool used to analyze mysql slow query logs. It can also analyze queries from "SHOW PROCESSLIST" and MySQL Protocol data in tcpdump. We can output the analysis log to a specified file and perform corresponding optimization and other operations by analyzing the log file.

2. Download and install

Install according to different systems. My system is centos, so I directly choose centos installation, Click to download
Use yum to install directly

> wget https://downloads.percona.com/downloads/percona-toolkit/3.4.0/binary/redhat/7/x86_64/percona-toolkit-3.4.0-3.el7.x86_64.rpm
> yum install percona-toolkit-3.4.0-3.el7.x86_64.rpm

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Or use the source code package to compile and install

> wget https://downloads.percona.com/downloads/percona-toolkit/3.4.0/source/debian/percona-toolkit-3.4.0.tar.gz
> tar -zxvf percona-toolkit-3.4.0.tar.gz
> cd percona-toolkit-3.4.0
> perl Makefile.PL PREFIX=/usr/local/percona-toolkit
> make && make install

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3. Installation completed

##4. Analysis of msql’s slow query log

perldoc /usr/bin/pt-query-digest

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pt-query-digest mysql-slow.log > slow_report.log

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pt-query-digest mysql-slow.log --since &#39;2022-10-01 00:00:00&#39; --until &#39;2022-11-05 00:00:00&#39;  > slow_report_date_20221021-202221105.log

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pt-query-digest --user=root --password=123456 --history 
h=192.168.33.10,D=local_test_db,t=query_review --create-history-table  mysql-slow.log  --since 
&#39;2022-11-01 00:00:00&#39; --until &#39;2022-11-05 00:00:00&#39;

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5. Result Analysis

Part 1: General analysis overview

Overall: How many queries are there in total
Time range: The time range of query execution
unique: The number of unique queries, that is, how many different queries there are after parameterizing the query conditions
total: Total duration of all queries
min: Minimum duration of all queries
max: All Maximum query duration
avg: Average query duration
95%: Arrange all duration values from small to large, and the position is at 95% That duration number, this number generally has the most reference value
median: Median, arranges all duration values from small to large, and the duration number located in the middle

# A software update is available:

# 23.7s user time, 15.8s system time, 35.67M rss, 249.01M 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，在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: Mon Nov  7 09:01:23 2022
说明：当前时间
# Hostname: localhost.localdomain
说明：执行pt-query-digest的主机名
# Files: mysql-slow.log
说明：被分析的文件名称
# Overall: 44.78k total, 54 unique, 0.01 QPS, 0.07x concurrency __________
说明：
total: 语句总数量
unique: 唯一语句数量
QPS: 每秒查询量
concurrency: 查询的并发

# Time range: 2022-10-01 00:00:03 to 2022-11-04 16:05:24
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
95%： 把所有时长值从小到大排列，位置位于 95% 的那个时长数，这个数一般最具有参考价值
median： 中位数，把所有时长值从小到大排列，位置位于中间那个时长数

# ============     ======= ======= ======= ======= ======= ======= =======
# Exec time        204553s      3s   1540s      5s     10s      8s      3s
说明：执行时间
# Lock time             8s       0   107ms   186us    80us     2ms    36us
说明：锁占用时间
# Rows sent        238.87M       0   2.88M   5.46k   11.95  68.22k    0.99
说明：发送到客户端的行数
# Rows examine      73.56G       0   5.01M   1.68M   3.86M 724.49k   1.32M
说明：扫描的语句行数
# Query size         8.18M      30   4.36k  191.46  511.45  224.63   72.65
说明：查询的字符数

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Part 2: Analysis

Rank: Ranking of all statements, by default arranged in descending order of query time, specified by –order-by
- Sort parameter introduction:
  sum Sum/total attribute value (default value)
  min Minimum attribute value (minimum value)
  max Maximum attribute value (minimum value)
  cnt Frequency/count of the query (by the number of times sql appears)
Query ID: statement ID (remove extra spaces and text characters, calculate hash value)
Response: Total response time
time: The query is in this The total time proportion in this analysis
Calls: the number of executions, that is, the total number of query statements of this type in this analysis
R/Call: Average response time per execution
V/M: Ratio of response time Variance-to-mean
Item : Query object

# Profile
说明：分析
# Rank Query ID                            Response time    Calls R/Call  
# ==== =================================== ================ ===== ======= 
#    1 0xC000AA97F210B2AEAE4933AF9B00296A  104236.2061 5... 30988  3.3638  0.03 SELECT xxx
#    2 0x974C6E6D54DB8B0DF505CA7BDC508686  32167.9607 15.7%  3418  9.4113  1.34 SELECT xxx 
#    3 0x6BE180C5804B585F25BB16550447DC6C  18453.0185  9.0%  2499  7.3842  0.92 SELECT xxx
#    4 0xADF16E3E9EB5D6B08245E39FF1428C9F  17873.4338  8.7%  3114  5.7397  0.84 SELECT xxx 
#    5 0x2964CD629A24595719659BDAEBCF0E6F  10648.5404  5.2%  1437  7.4103  0.93 SELECT xxx
#    6 0x50566E6DCF8FA562B88AE41AB1E32DC6   7424.3855  3.6%   303 24.5029 15.41 SELECT xxx
#    7 0xDB0A3D60F85C2212C476B144E1678AB8   5327.8370  2.6%  1627  3.2746  0.05 SELECT xxx
#    8 0x04BB0B332CEED517298AB06DE2A30AD6   3190.6822  1.6%   657  4.8564  1.36 SELECT xxx    
#   10 0xDAB0AF524151C621DC0E9B92AC002C38    526.6288  0.3%   140  3.7616  0.01 SELECT xxx 
# MISC 0xMISC                               1807.1067  0.9%    57 31.7036   0.0 <27 ITEMS>

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Part 3: Specific SQL statistics and analysis

pct: A certain execution attribute of this SQL statement accounts for all slow queries Percentage of an execution attribute of the statement
total: All attribute times of an execution attribute of the SQL statement.
Count: The number of times the sql statement is executed. The corresponding pct indicates that the number of execution times of this SQL statement accounts for the % of the number of execution times of all slow query statements (69% in the figure below), and the corresponding total indicates that a total of 30988 times were executed.
Exec time: sql execution time
Lock time: The time when sql is locked during execution
Rows sent: The valid data transmitted has a value only in the select query statement
Rows examine: The total queried data, non-target data.
Query_time distribution: Query time distribution
SQL statement: The picture below is select sleep(7)\G

# Query 1: 0.01 QPS, 0.03x concurrency, ID 0xC000AA97F210B2AEAE4933AF9B00296A at byte 221452362
说明：查询队列1：每秒查询量，查询的并发，队列1的ID值，对应第二部分的Query ID, 221452362表示偏移量(查看方法看下面的“查看偏移”)
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.03
# Time range: 2022-10-01 00:00:05 to 2022-11-04 16:05:24
说明：sql语句在慢日志文件mysql_slow.log出现的时间范围
# Attribute    pct   total     min     max     avg     95%  stddev  median
说明：属性      占整个 总数      最小值  最大值   平均值  95%   标准差  中间值
           分析中
           的百分
           比                
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count         69   30988
说明：执行语句总数量
# Exec time     50 104236s      3s      7s      3s      4s   303ms      3s
说明：执行时间
# Lock time     24      2s    22us    93ms    65us    66us   775us    38us
说明：锁占用时间
# Rows sent      0  70.53k       0     799    2.33    3.89   16.60    0.99
说明：发送到客户端的行数
# Rows examine  54  40.28G   1.32M   1.35M   1.33M   1.32M  15.65k   1.32M
说明：扫描语句的行数
# Query size    26   2.16M      73      73      73      73       0      73
说明：查询的字符数
# String:
# Hosts        localhost
说明：使用的数据主机IP
# Users        xxx
说明：使用的用户
# Query_time distribution
#   1us
#  10us
# 100us
#   1ms
#  10ms
# 100ms
#    1s  ################################################################
#  10s+
说明：查询时间分布
# Tables
#    SHOW TABLE STATUS LIKE &#39;xxx&#39;\G
#    SHOW CREATE TABLE `xxx`\G
# EXPLAIN /*!50100 PARTITIONS*/
select * from `table_name` where `updated_at` >= &#39;2022-10-15 00:00:40&#39;\G
说明：查询的mysql语句
第三部分是每一种查询比较慢的 sql 的详细统计结果
pct：该 sql 语句某执行属性占所有慢查询语句某执行属性的百分比
total：该 sql 语句某执行属性的所有属性时间。
Count：sql 语句执行的次数。
Exec time：sql 执行时间
Lock time：sql 执行期间被

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Six View Offset

[localhost]# tail -c +221452362 ./mysql-slow.log | head
t: root[root] @ localhost []  Id: 13704150
# Query_time: 7.058835  Lock_time: 0.000040 Rows_sent: 2  Rows_examined: 1392521
SET timestamp=1665763267;
select * from `xxxxxx` where `updated_at` >= &#39;2022-10-15 00:00:40&#39;;
# User@Host: root[localhost] @ localhost []  Id: 13704174
# Query_time: 7.445741  Lock_time: 0.000015 Rows_sent: 3  Rows_examined: 2214002
SET timestamp=1665763267;
select xxx from table where xxx
# Time: 221015 008
# User@Host: root[localhost] @ localhost []  Id: 13704414

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