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使用 pt-query-digest 分析 RDS MySQL 慢查询日志
前言
本文主要讲述如何使用 pt-query-digest 工具对 RDS MySQL 的 slow log 进行分析。
关于 RDS MySQL
MySQL 是世界上最流行的开源关系数据库，而 Amazon RDS 让你能够在云中轻松设置、操作和扩展 MySQL 部署。借助 Amazon RDS ，您可以在几分钟内快速部署可扩展的 MySQL 服务器，不仅经济实惠，还可以根据需要随时调整硬件容量的大小。
Amazon RDS for MySQL 可以管理备份、软件修补、监控、扩展和复制等耗时的数据库管理任务，让你能专注于应用程序开发和提供业务竞争力。
Amazon RDS 目前支持 5.5、5.6、5.7 和 8.0 版 MySQL Community Edition。
关于 pt-query-digest
对于数据库的日常管理工作，性能管理肯定会是占比最大的一块，“工欲善其事必先利其器”，一个好的性能分析工具会极大的提高数据库性能管理的效率，而 pt-query-digest 就是专门针对 MySQL 数据库慢查询日志的一个强力分析工具，相比于 mysqldumpslow ，其分析结果更加具体和完善。
pt-query-digest 属于 Percona Toolkit 工具集中最常用的一种，号称 MySQL DBA 必备工具之一，其能够分析MySQL数据库的 slow log 、 general log 、 binary log 文件，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。
安装 Percona Toolkit
安装最新的 percona release package
[root@ip-172-31-36-44 ~]# yum install https://repo.percona.com/yum/percona-release-latest.noarch.rpm
Loaded plugins: amazon-id, rhui-lb, search-disabled-repos
percona-release-latest.noarch.rpm | 16 kB 00:00:00
Examining /var/tmp/yum-root-jxf0g4/percona-release-latest.noarch.rpm: percona-release-1.0-9.noarch
Marking /var/tmp/yum-root-jxf0g4/percona-release-latest.noarch.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package percona-release.noarch 0:1.0-9 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=================================================================================================================================================================================
Package Arch Version Repository Size
=================================================================================================================================================================================
Installing:
percona-release noarch 1.0-9 /percona-release-latest.noarch 18 k
Transaction Summary
=================================================================================================================================================================================
Install 1 Package
Total size: 18 k
Installed size: 18 k
Is this ok [y/d/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : percona-release-1.0-9.noarch 1/1
* Enabling the Percona Original repository
<*> All done!
The percona-release package now contains a percona-release script that can enable additional repositories for our newer products.
For example, to enable the Percona Server 8.0 repository use:
percona-release setup ps80
Note: To avoid conflicts with older product versions, the percona-release setup command may disable our original repository for some products.
For more information, please visit:
https://www.percona.com/doc/percona-repo-config/percona-release.html
Verifying : percona-release-1.0-9.noarch 1/1
Installed:
percona-release.noarch 0:1.0-9
Complete!
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# ls -ltr /etc/yum.repos.d/
total 24
-rw-r--r--. 1 root root 8679 Mar 18 03:32 redhat-rhui.repo
-rw-r--r--. 1 root root 90 Mar 18 03:32 rhui-load-balancers.conf
-rw-r--r--. 1 root root 607 Mar 18 03:32 redhat-rhui-client-config.repo
-rw-r--r--. 1 root root 780 Mar 18 03:55 percona-original-release.repo
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# rpm -aq|grep percona
percona-release-1.0-9.noarch
percona-toolkit-3.0.13-1.el7.x86_64
[root@ip-172-31-36-44 ~]#
安装 percona toolkit
[root@ip-172-31-36-44 ~]# yum install percona-toolkit
Loaded plugins: amazon-id, rhui-lb, search-disabled-repos
Resolving Dependencies
--> Running transaction check
---> Package percona-toolkit.x86_64 0:3.0.13-1.el7 will be installed
--> Processing Dependency: perl(DBI) >= 1.13 for package: percona-toolkit-3.0.13-1.el7.x86_64
--> Processing Dependency: perl(DBD::mysql) >= 1.0 for package: percona-toolkit-3.0.13-1.el7.x86_64
--> Processing Dependency: perl(IO::Socket::SSL) for package: percona-toolkit-3.0.13-1.el7.x86_64
--> Processing Dependency: perl(Digest::MD5) for package: percona-toolkit-3.0.13-1.el7.x86_64
--> Processing Dependency: perl(Term::ReadKey) for package: percona-toolkit-3.0.13-1.el7.x86_64
--> Running transaction check
---> Package perl-DBD-MySQL.x86_64 0:4.023-6.el7 will be installed
---> Package perl-DBI.x86_64 0:1.627-4.el7 will be installed
--> Processing Dependency: perl(RPC::PlClient) >= 0.2000 for package: perl-DBI-1.627-4.el7.x86_64
--> Processing Dependency: perl(RPC::PlServer) >= 0.2001 for package: perl-DBI-1.627-4.el7.x86_64
--> Processing Dependency: perl(Data::Dumper) for package: perl-DBI-1.627-4.el7.x86_64
---> Package perl-Digest-MD5.x86_64 0:2.52-3.el7 will be installed
--> Processing Dependency: perl(Digest::base) >= 1.00 for package: perl-Digest-MD5-2.52-3.el7.x86_64
---> Package perl-IO-Socket-SSL.noarch 0:1.94-7.el7 will be installed
--> Processing Dependency: perl(IO::Socket::IP) >= 0.20 for package: perl-IO-Socket-SSL-1.94-7.el7.noarch
--> Processing Dependency: perl(Net::SSLeay) >= 1.21 for package: perl-IO-Socket-SSL-1.94-7.el7.noarch
--> Processing Dependency: perl-Net-SSLeay >= 1.55-5 for package: perl-IO-Socket-SSL-1.94-7.el7.noarch
--> Processing Dependency: perl(Mozilla::CA) for package: perl-IO-Socket-SSL-1.94-7.el7.noarch
--> Processing Dependency: perl(Net::LibIDN) for package: perl-IO-Socket-SSL-1.94-7.el7.noarch
--> Processing Dependency: perl(Net::SSLeay) for package: perl-IO-Socket-SSL-1.94-7.el7.noarch
---> Package perl-TermReadKey.x86_64 0:2.30-20.el7 will be installed
--> Running transaction check
---> Package perl-Data-Dumper.x86_64 0:2.145-3.el7 will be installed
---> Package perl-Digest.noarch 0:1.17-245.el7 will be installed
---> Package perl-IO-Socket-IP.noarch 0:0.21-5.el7 will be installed
---> Package perl-Mozilla-CA.noarch 0:20130114-5.el7 will be installed
---> Package perl-Net-LibIDN.x86_64 0:0.12-15.el7 will be installed
---> Package perl-Net-SSLeay.x86_64 0:1.55-6.el7 will be installed
---> Package perl-PlRPC.noarch 0:0.2020-14.el7 will be installed
--> Processing Dependency: perl(Net::Daemon) >= 0.13 for package: perl-PlRPC-0.2020-14.el7.noarch
--> Processing Dependency: perl(Compress::Zlib) for package: perl-PlRPC-0.2020-14.el7.noarch
--> Processing Dependency: perl(Net::Daemon::Log) for package: perl-PlRPC-0.2020-14.el7.noarch
--> Processing Dependency: perl(Net::Daemon::Test) for package: perl-PlRPC-0.2020-14.el7.noarch
--> Running transaction check
---> Package perl-IO-Compress.noarch 0:2.061-2.el7 will be installed
--> Processing Dependency: perl(Compress::Raw::Bzip2) >= 2.061 for package: perl-IO-Compress-2.061-2.el7.noarch
--> Processing Dependency: perl(Compress::Raw::Zlib) >= 2.061 for package: perl-IO-Compress-2.061-2.el7.noarch
---> Package perl-Net-Daemon.noarch 0:0.48-5.el7 will be installed
--> Running transaction check
---> Package perl-Compress-Raw-Bzip2.x86_64 0:2.061-3.el7 will be installed
---> Package perl-Compress-Raw-Zlib.x86_64 1:2.061-4.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=================================================================================================================================================================================
Package Arch Version Repository Size
=================================================================================================================================================================================
Installing:
percona-toolkit x86_64 3.0.13-1.el7 percona-release-x86_64 7.4 M
Installing for dependencies:
perl-Compress-Raw-Bzip2 x86_64 2.061-3.el7 rhui-REGION-rhel-server-releases 32 k
perl-Compress-Raw-Zlib x86_64 1:2.061-4.el7 rhui-REGION-rhel-server-releases 57 k
perl-DBD-MySQL x86_64 4.023-6.el7 rhui-REGION-rhel-server-releases 140 k
perl-DBI x86_64 1.627-4.el7 rhui-REGION-rhel-server-releases 802 k
perl-Data-Dumper x86_64 2.145-3.el7 rhui-REGION-rhel-server-releases 47 k
perl-Digest noarch 1.17-245.el7 rhui-REGION-rhel-server-releases 23 k
perl-Digest-MD5 x86_64 2.52-3.el7 rhui-REGION-rhel-server-releases 30 k
perl-IO-Compress noarch 2.061-2.el7 rhui-REGION-rhel-server-releases 260 k
perl-IO-Socket-IP noarch 0.21-5.el7 rhui-REGION-rhel-server-releases 36 k
perl-IO-Socket-SSL noarch 1.94-7.el7 rhui-REGION-rhel-server-releases 114 k
perl-Mozilla-CA noarch 20130114-5.el7 rhui-REGION-rhel-server-releases 11 k
perl-Net-Daemon noarch 0.48-5.el7 rhui-REGION-rhel-server-releases 51 k
perl-Net-LibIDN x86_64 0.12-15.el7 rhui-REGION-rhel-server-releases 28 k
perl-Net-SSLeay x86_64 1.55-6.el7 rhui-REGION-rhel-server-releases 286 k
perl-PlRPC noarch 0.2020-14.el7 rhui-REGION-rhel-server-releases 36 k
perl-TermReadKey x86_64 2.30-20.el7 rhui-REGION-rhel-server-releases 31 k
Transaction Summary
=================================================================================================================================================================================
Install 1 Package (+16 Dependent packages)
Total download size: 9.4 M
Installed size: 12 M
Is this ok [y/d/N]: y
Downloading packages:
(1/17): perl-Compress-Raw-Bzip2-2.061-3.el7.x86_64.rpm | 32 kB 00:00:00
(2/17): perl-Compress-Raw-Zlib-2.061-4.el7.x86_64.rpm | 57 kB 00:00:00
(3/17): perl-DBD-MySQL-4.023-6.el7.x86_64.rpm | 140 kB 00:00:00
(4/17): perl-Data-Dumper-2.145-3.el7.x86_64.rpm | 47 kB 00:00:00
(5/17): perl-DBI-1.627-4.el7.x86_64.rpm | 802 kB 00:00:00
(6/17): perl-Digest-1.17-245.el7.noarch.rpm | 23 kB 00:00:00
(7/17): perl-Digest-MD5-2.52-3.el7.x86_64.rpm | 30 kB 00:00:00
(8/17): perl-IO-Compress-2.061-2.el7.noarch.rpm | 260 kB 00:00:00
(9/17): perl-IO-Socket-IP-0.21-5.el7.noarch.rpm | 36 kB 00:00:00
(10/17): perl-IO-Socket-SSL-1.94-7.el7.noarch.rpm | 114 kB 00:00:00
(11/17): perl-Mozilla-CA-20130114-5.el7.noarch.rpm | 11 kB 00:00:00
(12/17): perl-Net-Daemon-0.48-5.el7.noarch.rpm | 51 kB 00:00:00
(13/17): perl-Net-LibIDN-0.12-15.el7.x86_64.rpm | 28 kB 00:00:00
(14/17): perl-PlRPC-0.2020-14.el7.noarch.rpm | 36 kB 00:00:00
(15/17): perl-Net-SSLeay-1.55-6.el7.x86_64.rpm | 286 kB 00:00:00
(16/17): perl-TermReadKey-2.30-20.el7.x86_64.rpm | 31 kB 00:00:00
(17/17): percona-toolkit-3.0.13-1.el7.x86_64.rpm | 7.4 MB 00:00:03
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 2.4 MB/s | 9.4 MB 00:00:03
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : perl-Digest-1.17-245.el7.noarch 1/17
Installing : perl-Digest-MD5-2.52-3.el7.x86_64 2/17
Installing : perl-Compress-Raw-Bzip2-2.061-3.el7.x86_64 3/17
Installing : perl-Net-LibIDN-0.12-15.el7.x86_64 4/17
Installing : 1:perl-Compress-Raw-Zlib-2.061-4.el7.x86_64 5/17
Installing : perl-IO-Compress-2.061-2.el7.noarch 6/17
Installing : perl-Net-SSLeay-1.55-6.el7.x86_64 7/17
Installing : perl-IO-Socket-IP-0.21-5.el7.noarch 8/17
Installing : perl-Data-Dumper-2.145-3.el7.x86_64 9/17
Installing : perl-TermReadKey-2.30-20.el7.x86_64 10/17
Installing : perl-Net-Daemon-0.48-5.el7.noarch 11/17
Installing : perl-PlRPC-0.2020-14.el7.noarch 12/17
Installing : perl-DBI-1.627-4.el7.x86_64 13/17
Installing : perl-DBD-MySQL-4.023-6.el7.x86_64 14/17
Installing : perl-Mozilla-CA-20130114-5.el7.noarch 15/17
Installing : perl-IO-Socket-SSL-1.94-7.el7.noarch 16/17
Installing : percona-toolkit-3.0.13-1.el7.x86_64 17/17
Verifying : perl-Mozilla-CA-20130114-5.el7.noarch 1/17
Verifying : perl-Net-Daemon-0.48-5.el7.noarch 2/17
Verifying : perl-TermReadKey-2.30-20.el7.x86_64 3/17
Verifying : perl-Data-Dumper-2.145-3.el7.x86_64 4/17
Verifying : perl-Digest-MD5-2.52-3.el7.x86_64 5/17
Verifying : perl-IO-Socket-IP-0.21-5.el7.noarch 6/17
Verifying : percona-toolkit-3.0.13-1.el7.x86_64 7/17
Verifying : perl-DBD-MySQL-4.023-6.el7.x86_64 8/17
Verifying : perl-PlRPC-0.2020-14.el7.noarch 9/17
Verifying : perl-Net-SSLeay-1.55-6.el7.x86_64 10/17
Verifying : 1:perl-Compress-Raw-Zlib-2.061-4.el7.x86_64 11/17
Verifying : perl-Net-LibIDN-0.12-15.el7.x86_64 12/17
Verifying : perl-Compress-Raw-Bzip2-2.061-3.el7.x86_64 13/17
Verifying : perl-Digest-1.17-245.el7.noarch 14/17
Verifying : perl-DBI-1.627-4.el7.x86_64 15/17
Verifying : perl-IO-Compress-2.061-2.el7.noarch 16/17
Verifying : perl-IO-Socket-SSL-1.94-7.el7.noarch 17/17
Installed:
percona-toolkit.x86_64 0:3.0.13-1.el7
Dependency Installed:
perl-Compress-Raw-Bzip2.x86_64 0:2.061-3.el7 perl-Compress-Raw-Zlib.x86_64 1:2.061-4.el7 perl-DBD-MySQL.x86_64 0:4.023-6.el7 perl-DBI.x86_64 0:1.627-4.el7
perl-Data-Dumper.x86_64 0:2.145-3.el7 perl-Digest.noarch 0:1.17-245.el7 perl-Digest-MD5.x86_64 0:2.52-3.el7 perl-IO-Compress.noarch 0:2.061-2.el7
perl-IO-Socket-IP.noarch 0:0.21-5.el7 perl-IO-Socket-SSL.noarch 0:1.94-7.el7 perl-Mozilla-CA.noarch 0:20130114-5.el7 perl-Net-Daemon.noarch 0:0.48-5.el7
perl-Net-LibIDN.x86_64 0:0.12-15.el7 perl-Net-SSLeay.x86_64 0:1.55-6.el7 perl-PlRPC.noarch 0:0.2020-14.el7 perl-TermReadKey.x86_64 0:2.30-20.el7
Complete!
[root@ip-172-31-36-44 ~]#
验证 pt-queyr-digest 是否可以使用
[root@ip-172-31-36-44 ~]# pt-query-digest --help
pt-query-digest analyzes MySQL queries from slow, general, and binary log files.
It can also analyze queries from C<SHOW PROCESSLIST> and MySQL protocol data
from tcpdump. By default, queries are grouped by fingerprint and reported in
descending order of query time (i.e. the slowest queries first). If no C<FILES>
are given, the tool reads C<STDIN>. The optional C<DSN> is used for certain
options like L<"--since"> and L<"--until">. For more details, please use the
--help option, or try 'perldoc /bin/pt-query-digest' for complete documentation.
Usage: pt-query-digest [OPTIONS] [FILES] [DSN]
Options:
--ask-pass Prompt for a password when connecting to MySQL
--attribute-aliases=a List of attribute|alias,etc (default db|Schema)
--attribute-value-limit=i A sanity limit for attribute values (default 0)
--charset=s -A Default character set
--config=A Read this comma-separated list of config files;
if specified, this must be the first option on
the command line
--[no]continue-on-error Continue parsing even if there is an error (
default yes)
--[no]create-history-table Create the --history table if it does not exist (
default yes)
--[no]create-review-table Create the --review table if it does not exist (
default yes)
--daemonize Fork to the background and detach from the shell
--database=s -D Connect to this database
--defaults-file=s -F Only read mysql options from the given file
--embedded-attributes=a Two Perl regex patterns to capture pseudo-
attributes embedded in queries
--expected-range=a Explain items when there are more or fewer than
expected (default 5,10)
--explain=d Run EXPLAIN for the sample query with this DSN
and print results
--filter=s Discard events for which this Perl code doesn't
return true
--group-by=A Which attribute of the events to group by (
default fingerprint)
--help Show help and exit
--history=d Save metrics for each query class in the given
table. pt-query-digest saves query metrics (
query time, lock time, etc.) to this table so
you can see how query classes change over time
--host=s -h Connect to host
--ignore-attributes=a Do not aggregate these attributes (default arg,
cmd, insert_id, ip, port, Thread_id, timestamp,
exptime, flags, key, res, val, server_id,
offset, end_log_pos, Xid)
--inherit-attributes=a If missing, inherit these attributes from the
last event that had them (default db,ts)
--interval=f How frequently to poll the processlist, in
seconds (default .1)
--iterations=i How many times to iterate through the collect-
and-report cycle (default 1)
--limit=A Limit output to the given percentage or count (
default 95%:20)
--log=s Print all output to this file when daemonized
--max-hostname-length=i Trim host names in reports to this length. 0=Do
not trim host names (default 10)
--max-line-length=i Trim lines to this length. 0=Do not trim lines (
default 74)
--order-by=A Sort events by this attribute and aggregate
function (default Query_time:sum)
--outliers=a Report outliers by attribute:percentile:count (
default Query_time:1:10)
--output=s How to format and print the query analysis
results (default report)
--password=s -p Password to use when connecting
--pid=s Create the given PID file
--port=i -P Port number to use for connection
--preserve-embedded-numbers Preserve numbers in database/table names when
fingerprinting queries
--processlist=d Poll this DSN's processlist for queries, with --
interval sleep between
--progress=a Print progress reports to STDERR (default time,
30)
--read-timeout=m Wait this long for an event from the input; 0 to
wait forever (default 0). Optional suffix s=
seconds, m=minutes, h=hours, d=days; if no
suffix, s is used.
--[no]report Print query analysis reports for each --group-by
attribute (default yes)
--report-all Report all queries, even ones that have been
reviewed
--report-format=A Print these sections of the query analysis
report (default rusage,date,hostname,files,
header,profile,query_report,prepared)
--report-histogram=s Chart the distribution of this attribute's
values (default Query_time)
--resume=s If specified, the tool writes the last file
offset, if there is one, to the given filename
--review=d Save query classes for later review, and don't
report already reviewed classes
--run-time=m How long to run for each --iterations. Optional
suffix s=seconds, m=minutes, h=hours, d=days; if
no suffix, s is used.
--run-time-mode=s Set what the value of --run-time operates on (
default clock)
--sample=i Filter out all but the first N occurrences of
each query
--set-vars=A Set the MySQL variables in this comma-separated
list of variable=value pairs
--show-all=H Show all values for these attributes
--since=s Parse only queries newer than this value (parse
queries since this date)
--slave-password=s Sets the password to be used to connect to the
slaves
--slave-user=s Sets the user to be used to connect to the slaves
--socket=s -S Socket file to use for connection
--timeline Show a timeline of events
--type=A The type of input to parse (default slowlog)
--until=s Parse only queries older than this value (parse
queries until this date)
--user=s -u User for login if not current user
--variations=A Report the number of variations in these
attributes' values
--version Show version and exit
--[no]version-check Check for the latest version of Percona Toolkit,
MySQL, and other programs (default yes)
--[no]vertical-format Output a trailing "\G" in the reported SQL
queries (default yes)
--watch-server=s This option tells pt-query-digest which server
IP address and port (like "10.0.0.1:3306") to
watch when parsing tcpdump (for --type tcpdump);
all other servers are ignored
Option types: s=string, i=integer, f=float, h/H/a/A=comma-separated list, d=DSN, z=size, m=time
Rules:
This tool accepts additional command-line arguments. Refer to the SYNOPSIS and usage information for details.
DSN syntax is key=value[,key=value...] Allowable DSN keys:
KEY COPY MEANING
=== ==== =============================================
A yes Default character set
D yes Default database to use when connecting to MySQL
F yes Only read default options from the given file
P yes Port number to use for connection
S yes Socket file to use for connection
h yes Connect to host
p yes Password to use when connecting
t no The --review or --history table
u yes User for login if not current user
If the DSN is a bareword, the word is treated as the 'h' key.
Options and values after processing arguments:
--ask-pass FALSE
--attribute-aliases db|Schema
--attribute-value-limit 0
--charset (No value)
--config /etc/percona-toolkit/percona-toolkit.conf,/etc/percona-toolkit/pt-query-digest.conf,/root/.percona-toolkit.conf,/root/.pt-query-digest.conf
--continue-on-error TRUE
--create-history-table TRUE
--create-review-table TRUE
--daemonize FALSE
--database (No value)
--defaults-file (No value)
--embedded-attributes (No value)
--expected-range 5,10
--explain (No value)
--filter (No value)
--group-by fingerprint
--help TRUE
--history (No value)
--host (No value)
--ignore-attributes arg,cmd,insert_id,ip,port,Thread_id,timestamp,exptime,flags,key,res,val,server_id,offset,end_log_pos,Xid
--inherit-attributes db,ts
--interval .1
--iterations 1
--limit 95%:20
--log (No value)
--max-hostname-length 10
--max-line-length 74
--order-by Query_time:sum
--outliers Query_time:1:10
--output report
--password (No value)
--pid (No value)
--port (No value)
--preserve-embedded-numbers FALSE
--processlist (No value)
--progress time,30
--read-timeout 0
--report TRUE
--report-all FALSE
--report-format rusage,date,hostname,files,header,profile,query_report,prepared
--report-histogram Query_time
--resume (No value)
--review (No value)
--run-time (No value)
--run-time-mode clock
--sample (No value)
--set-vars
--show-all
--since (No value)
--slave-password (No value)
--slave-user (No value)
--socket (No value)
--timeline FALSE
--type slowlog
--until (No value)
--user (No value)
--variations
--version FALSE
--version-check TRUE
--vertical-format TRUE
--watch-server (No value)
[root@ip-172-31-36-44 ~]#
安装及配置 AWSCLI
这里安装awscli主要是为了后续可以使用awscli下载RDS MySQL的slow log文件到本地，供pt-query-digest进行分析。
安装 awscli
curl "https://s3.amazonaws.com/aws-cli/awscli-bundle.zip" -o "awscli-bundle.zip"
unzip awscli-bundle.zip
./awscli-bundle/install
echo "export PATH=$PATH:/root/.local/lib/aws/bin" >> ~/.bash_profile
source ~/.bash_profile
cat ~/.bash_profile
配置 awscli
[root@ip-172-31-36-44 ~]# aws configure
AWS Access Key ID [None]: AKIAXXXXXXXX6PPVDJKQ
AWS Secret Access Key [None]: BhlGgQLOjEcxxxxx/w3JxxxxxxUCI4IAra92ZJ
Default region name [None]: cn-northwest-1
Default output format [None]:
[root@ip-172-31-36-44 ~]#
安装 MySQL 客户端
这里安装MySQL客户端主要是为了后续可以使用mysql命令进行相关sql语句的执行，以获取RDS MySQL的slow log文件到本地，供pt-query-digest进行分析。
[root@ip-172-31-36-44 ~]# yum install mariadb.x86_64 -y
Loaded plugins: amazon-id, rhui-lb, search-disabled-repos
Resolving Dependencies
--> Running transaction check
---> Package mariadb.x86_64 1:5.5.60-1.el7_5 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=================================================================================================================================================================================
Package Arch Version Repository Size
=================================================================================================================================================================================
Installing:
mariadb x86_64 1:5.5.60-1.el7_5 rhui-REGION-rhel-server-releases 8.6 M
Transaction Summary
=================================================================================================================================================================================
Install 1 Package
Total download size: 8.6 M
Installed size: 49 M
Downloading packages:
mariadb-5.5.60-1.el7_5.x86_64.rpm | 8.6 MB 00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : 1:mariadb-5.5.60-1.el7_5.x86_64 1/1
Verifying : 1:mariadb-5.5.60-1.el7_5.x86_64 1/1
Installed:
mariadb.x86_64 1:5.5.60-1.el7_5
Complete!
[root@ip-172-31-36-44 ~]#
使用 pt-query-digest 分析 slow log
前面我们已经完成了所有的准备工作，现在看看如何来使用 pt-query-digest 工具分析 RDS MySQL 的 slow log 文件。
如果要分析 slow log，第一步就是先要获取到 slow log 文件，由于 RDS MySQL 是托管数据库，我们无法登录到 MySQL 所在服务器，那么应该如何来获取 slow log 文件呢？
根据 MySQL slow log 的相关配置，我们知道 slow log 的存在形式一共有两种： table 或 file ，由 log_output 参数进行控制：
- TABLE (默认) – 将一般查询写入 general_log 表，将慢速查询写入 mysql.slow_log 表；
- FILE – 将一般查询日志和慢速查询日志写入文件系统；
- NONE – 禁用日志记录；
针对不同形式的 slow log，我们有不同的方法将其下载到本地：
- TABLE ：由于这是将慢查询记录存放在 MySQL 的数据表里，这里我们可以使用 sql 命令将其输出到本地的一个文件；
- FILE ：慢查询日志存放在 RDS MySQL 托管主机上，我们可以利用 awscli 提供的 RDS API download-db-log-file-portion 将 slow log 下载到本地；
具体实现形式请参加后续对应部分的内容。
使用 sql 脚本获取 slow log
获取整个 slow log
mysql> show variables like 'log_output';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_output | TABLE |
+---------------+-------+
1 row in set (0.03 sec)
mysql>
[root@ip-172-31-36-44 ~]# mysql -h mysql.xxxxxxxxxxxx.rds.cn-northwest-1.amazonaws.com.cn -u root -p -P13306 -D mysql -s -r -e "SELECT CONCAT( '# Time: ', DATE_FORMAT(start_time, '%y%m%d %H%i%s'), '\n', '# User@Host: ', user_host, '\n', '# Query_time: ', TIME_TO_SEC(query_time), ' Lock_time: ', TIME_TO_SEC(lock_time), ' Rows_sent: ', rows_sent, ' Rows_examined: ', rows_examined, '\n', sql_text, ';' ) FROM mysql.slow_log" > /tmp/mysql_slow_log.log
Enter password:
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# ls -l /tmp/mysql_slow_log.log
-rw-r--r--. 1 root root 14211651 Mar 19 02:57 /tmp/mysql_slow_log.log
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# more /tmp/mysql_slow_log.log
# Time: 190130 145734
# User@Host: root[root] @ [60.223.227.126]
# Query_time: 20 Lock_time: 0 Rows_sent: 0 Rows_examined: 48413563
select * from unit_value where FT121_SET <> null
LIMIT 0, 10000;
# Time: 190130 153530
# User@Host: root[root] @ 42-2-128-026.static.netvigator.com [42.2.128.26]
# Query_time: 96 Lock_time: 0 Rows_sent: 20099504 Rows_examined: 68517265
select PT111_VALUE from unit_value WHERE PT111_VALUE <> 0 and PT111_VALUE < 1.3 ORDER by UNITNAME DESC;
# Time: 190130 153802
# User@Host: root[root] @ 42-2-128-026.static.netvigator.com [42.2.128.26]
# Query_time: 31 Lock_time: 0 Rows_sent: 579105 Rows_examined: 49576551
select DISTINCT UNITNAME,PT111_VALUE from unit_value WHERE PT111_VALUE <> 0 and PT111_VALUE < 1.3 ORDER by UNITNAME DESC;
# Time: 190130 154215
# User@Host: root[root] @ [60.223.227.126]
# Query_time: 45 Lock_time: 0 Rows_sent: 1580250 Rows_examined: 50026401
select
UNITNAME
,first_value(PT111_VALUE) over (partition by UNITNAME order by UNITTIME)
from unit_value;
获取指定时间段的 slow log
[root@ip-172-31-36-44 ~]# mysql -h mysql.xxxxxxxxxxxx.rds.cn-northwest-1.amazonaws.com.cn -u root -p -P13306 -D mysql -s -r -e "SELECT CONCAT( '# Time: ', DATE_FORMAT(start_time, '%y%m%d %H%i%s'), '\n', '# User@Host: ', user_host, '\n', '# Query_time: ', TIME_TO_SEC(query_time), ' Lock_time: ', TIME_TO_SEC(lock_time), ' Rows_sent: ', rows_sent, ' Rows_examined: ', rows_examined, '\n', sql_text, ';' ) FROM mysql.slow_log where DATE_FORMAT(start_time, '%Y%m%d %H:%i:%s') between '20190328 10:00:00' and '20190328 11:00:00' " > /tmp/slow.log.10-11.log
Enter password:
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# ls -l /tmp/mysql_slow_log1.log
-rw-r--r--. 1 root root 10874816 Mar 19 04:33 /tmp/mysql_slow_log1.log
[root@ip-172-31-36-44 ~]#
使用 awscli 获取 MySQL slow log
mysql> show variables like '%output%';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| innodb_status_output | OFF |
| innodb_status_output_locks | OFF |
| log_output | FILE |
+----------------------------+-------+
3 rows in set (0.05 sec)
mysql>
mysql> show variables like '%slow%';
+---------------------------+----------------------------------------------+
| Variable_name | Value |
+---------------------------+----------------------------------------------+
| log_slow_admin_statements | OFF |
| log_slow_slave_statements | OFF |
| slow_launch_time | 2 |
| slow_query_log | ON |
| slow_query_log_file | /rdsdbdata/log/slowquery/mysql-slowquery.log |
+---------------------------+----------------------------------------------+
5 rows in set (2.07 sec)
mysql>
[root@ip-172-31-36-44 ~]# aws rds download-db-log-file-portion --db-instance-identifier mysql --log-file-name slowquery/mysql-slowquery.log --starting-token 0 --output text> mysql-slowquery.log
[root@ip-172-31-36-44 ~]# ls -l mysql-slowquery.log
-rw-r--r--. 1 root root 15970 Mar 19 04:41 mysql-slowquery.log
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# more mysql-slowquery.log
# Time: 2019-03-19T04:40:56.629552Z
# User@Host: root[root] @ ec2-52-82-53-253.cn-northwest-1.compute.amazonaws.com.cn [52.82.53.253] Id: 249635335
# Query_time: 5.087165 Lock_time: 0.000052 Rows_sent: 0 Rows_examined: 1496709
use yuci;
SET timestamp=1552970456;
SELECT tagout_value.tagtime AS tagout_value_tagtime, tagout_value.tagname AS tagout_value_tagname, tagout_value.tagvalue AS tagout_value_tagvalue
FROM tagout_value
WHERE tagout_value.tagname = 'COV122_OUTPAR_134' ORDER BY tagout_value.tagtime DESC
LIMIT 1;
# Time: 2019-03-19T04:40:56.819594Z
# User@Host: root[root] @ ec2-52-82-59-190.cn-northwest-1.compute.amazonaws.com.cn [52.82.59.190] Id: 249635331
# Query_time: 5.274261 Lock_time: 0.000053 Rows_sent: 0 Rows_examined: 1496709
SET timestamp=1552970456;
SELECT tagout_value.tagtime AS tagout_value_tagtime, tagout_value.tagname AS tagout_value_tagname, tagout_value.tagvalue AS tagout_value_tagvalue
FROM tagout_value
WHERE tagout_value.tagname = 'COV122_OUTPAR' ORDER BY tagout_value.tagtime DESC
LIMIT 1;
实际案例
这里描述一个实际的案例，在 RDS MySQL 碰到性能问题时，我们如何通过 pt-query-digest 工具来分析性能，找到其中的问题所在。
发现问题
某一天突然发现 RDS MySQL CPU 利用率高达100%，平时正常运行几乎都在40%以下，怀疑 MySQL 数据库之前运行了一些问题 SQL 语句导致了 CPU 资源的飙升。
分析问题
这里我们首先来获取13:00-14:00这一个小时范围内的 RDS MySQL slow log ，然后再使用我们前面部署的 pt-query-digest 工具来分析一下，看是否可以发现一些端倪。
[root@ip-172-31-36-44 ~]# mysql -h mysql. xxxxxxxxxxxx.rds.cn-northwest-1.amazonaws.com.cn -u root -p -P13306 -D mysql -s -r -e "SELECT CONCAT( '# Time: ', DATE_FORMAT(start_time, '%y%m%d %H%i%s'), '\n', '# User@Host: ', user_host, '\n', '# Query_time: ', TIME_TO_SEC(query_time), ' Lock_time: ', TIME_TO_SEC(lock_time), ' Rows_sent: ', rows_sent, ' Rows_examined: ', rows_examined, '\n', sql_text, ';' ) FROM mysql.slow_log where DATE_FORMAT(start_time, '%Y%m%d %H:%i:%s') between '20190328 13:00:00' and '20190328 14:00:00' " > /tmp/slow.log.1314.log
Enter password:
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# pt-query-digest --report /tmp/slow.log.1314.log> /tmp/report.1314.log
[root@ip-172-31-36-44 ~]#
[root@ip-172-31-36-44 ~]# cat /tmp/report.1314.log
# 220ms user time, 30ms system time, 27.48M rss, 221.73M vsz
# Current date: Thu Mar 28 06:03:53 2019
# Hostname: ip-172-31-36-44.cn-northwest-1.compute.internal
# Files: /tmp/slow.log.1314.log
# Overall: 255 total, 4 unique, 0 QPS, 0x concurrency ____________________
# Attribute total min max avg 95% stddev median
# ============ ======= ======= ======= ======= ======= ======= =======
# Exec time 9360s 5s 62s 37s 49s 8s 35s
# Lock time 0 0 0 0 0 0 0
# Rows sent 3.12k 0 266 12.52 0 54.70 0
# Rows examine 1.85G 1.88M 12.99M 7.45M 9.30M 1.35M 6.94M
# Query size 2.42M 78 114.10k 9.72k 79.83k 28.60k 212.52
# Time 46.29M 185.87k 185.87k 185.87k 185.87k 0 185.87k
# Profile
# Rank Query ID Response time Calls R/Call V/M
# ==== ============================== =============== ===== ======= =====
# 1 0x582C46632FB388ABE5D178303... 7913.0000 84.5% 216 36.6343 1.57 SELECT MLModel?_ecgw_a_pred
# 2 0x0E39F3F13EDA325B4E53D0244... 971.0000 10.4% 25 38.8400 2.04 INSERT slph_adjust_his
# 3 0x3FC5160B3B25069FA843DC222... 466.0000 5.0% 12 38.8333 1.53 SELECT MLModel?_jd_pred unit_info MLModel?_jd_pred
# MISC 0xMISC 10.0000 0.1% 2 5.0000 0.0 <1 ITEMS>
# Query 1: 0 QPS, 0x concurrency, ID 0x582C46632FB388ABE5D178303E079908 at byte 420282
# This item is included in the report because it matches --limit.
# Scores: V/M = 1.57
# Attribute pct total min max avg 95% stddev median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count 84 216
# Exec time 84 7913s 20s 57s 37s 49s 8s 35s
# Lock time 0 0 0 0 0 0 0 0
# Rows sent 0 0 0 0 0 0 0 0
# Rows examine 79 1.48G 7.01M 7.02M 7.02M 6.94M 0 6.94M
# Query size 1 47.02k 222 223 222.89 212.52 0 212.52
# Time 84 39.21M 185.87k 185.87k 185.87k 185.87k 0 185.87k
# String:
# Hosts 172.31.39.23 (120/55%), 172.31.46.35 (36/16%)... 3 more
# Users root
# Query_time distribution
# 1us
# 10us
# 100us
# 1ms
# 10ms
# 100ms
# 1s
# 10s+ ################################################################
# Tables
# SHOW TABLE STATUS LIKE 'MLModel6_ecgw_a_pred'\G
# SHOW CREATE TABLE `MLModel6_ecgw_a_pred`\G
# EXPLAIN /*!50100 PARTITIONS*/
SELECT * FROM MLModel6_ecgw_a_pred
where unitname = 395 and forecast48hr >= now()
and forecast48hr < NOW() + INTERVAL 1 HOUR
order by predTime desc
limit 1\G
# Query 2: 0 QPS, 0x concurrency, ID 0x0E39F3F13EDA325B4E53D0244F2E9A23 at byte 210412
..............
..............
..............
从上面我们可以看到排在第一位的 SQL 语句在本次分析中总的时间占比高达84%，且单次调用耗时在36秒。接下来我们看看 SQL 语句的情况：
mysql> SELECT * FROM MLModel6_ecgw_a_pred
-> where unitname = 395 and forecast48hr >= now()
-> and forecast48hr < NOW() + INTERVAL 1 HOUR
-> order by predTime desc
-> limit 1
-> ;
Empty set (39.59 sec)
mysql> explain SELECT * FROM MLModel6_ecgw_a_pred
-> where unitname = 395 and forecast48hr >= now()
-> and forecast48hr < NOW() + INTERVAL 1 HOUR
-> order by predTime desc
-> limit 1;
+----+-------------+----------------------+------------+-------+---------------+---------+---------+------+------+----------+----------------------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+----------------------+------------+-------+---------------+---------+---------+------+------+----------+----------------------------------+
| 1 | SIMPLE | MLModel6_ecgw_a_pred | NULL | index | idx_un | idx_un1 | 15 | NULL | 325 | 0.03 | Using where; Backward index scan |
+----+-------------+----------------------+------------+-------+---------------+---------+---------+------+------+----------+----------------------------------+
1 row in set, 1 warning (0.02 sec)
mysql> show index from MLModel6_ecgw_a_pred;
+----------------------+------------+----------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression |
+----------------------+------------+----------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| MLModel6_ecgw_a_pred | 0 | PRIMARY | 1 | id | A | 6899295 | NULL | NULL | | BTREE | | | YES | NULL |
| MLModel6_ecgw_a_pred | 1 | idx_un | 1 | forecast48hr | A | 60106 | NULL | NULL | YES | BTREE | | | YES | NULL |
| MLModel6_ecgw_a_pred | 1 | idx_un | 2 | UNITNAME | A | 352164 | NULL | NULL | YES | BTREE | | | YES | NULL |
| MLModel6_ecgw_a_pred | 1 | idx_un1 | 1 | predTime | A | 112492 | NULL | NULL | YES | BTREE | | | YES | NULL |
| MLModel6_ecgw_a_pred | 1 | idx_un1 | 2 | UNITNAME | A | 162489 | NULL | NULL | YES | BTREE | | | YES | NULL |
+----------------------+------------+----------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
5 rows in set (0.10 sec)
mysql>
从上面我们不难看出，此 SQL 语句使用了错误的索引 idx_un1 ，实际上使用 idx_un 索引选择性会更好，执行效率会更高。
解决问题
强制此 SQL 语句使用正确的索引，不到1秒就执行完毕：
mysql> SELECT * FROM MLModel6_ecgw_a_pred force index(idx_un)
-> where unitname = 395 and forecast48hr >= now()
-> and forecast48hr < NOW() + INTERVAL 1 HOUR
-> order by predTime desc
-> limit 1
-> ;
Empty set (0.03 sec)
mysql>
后续就是具体的优化工作，至于是优化索引设置，还是去调整SQL语句，可以根据实际情况来进行即可。
总结
- pt-query-digest 是一个针对 MySQL slow log 进行分析的工具，可以获得更友好、易读、更人性化的 SQL 性能汇总及分析报告；
- RDS MySQL 由于是托管的数据库，我们可以使用 awscli RDS API 或者以 MySQL sql 脚本来分别将 FILE 和 TABLE 形式的慢查询日志获取到本地，然后再使用 pt-query-digest 进行分析；
- Percona Toolkit 是业界比较知名的 MySQL 工具集，里面包含多种可以提升效率的管理工具，除了 pt-query-digest 使用较多之外，还有 pt-online-schema-change 、 pt-mysql-summary 、 pt-summary 等工具被广泛使用，推荐有兴趣的同学可以尝试使用；