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PMM2 apt installation turns of slow query log

Hi,
I upgraded the PMM clients on several Debian servers (9.11 and 9.12) running MySQL 5.6 and 5.7 from PMM1 to PMM2, using the Percona repository. Basically "apt update; apt install pmm2-client".
I noticed on every one of those servers that the MySQL slow query log became disabled after running "apt install pmm2-client".
Is that a bug or a feature I don't understand?
Greetings,
Steffen

Best Answer

Answers

  • PeterPeter Percona CEO Percona Moderator Role
    Are you sure it is PMM2 installation NOT PMM1 Removal which disabled Slow Query Log ? 

  • steffensteffen Current User Role Supporter
    Can't tell, since "apt install pmm2-client" does both in one step.
    But either way, I had slow query log enabled even before installing the pmm1 clients, so it think it's not good to disable it when uninstalling. Luckily I have a custom dashboard that shows me all those flags, so I noticed right away.
    If it is an expected behavior, maybe you should add a hint to the docs or the blog posts about the upgrading process.
  • lalit.choudharylalit.choudhary Percona Percona Staff Role
    Hi  @steffen
    I do not see the described case in my test, tested on Debian 9 and ubuntu18 with mysql 5.7 version with slow+log enabled. upgrading from pmm1 to pmm 2 client using apt install not affecting slow_log settings in mysql. 

    Test:
    # cat /etc/debian_version 
    9.6
    mysql 5.7.30
    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       | /var/lib/mysql/ip-172-30-3-190-slow.log |
    +---------------------------+-----------------------------------------+
    5 rows in set (0.00 sec)

    mysql> exit
    Bye
    # apt install pmm2-client
    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    The following packages were automatically installed and are no longer required:
      galera-3 libcgi-fast-perl libcgi-pm-perl libconfig-inifiles-perl libdbd-mysql-perl libdbi-perl libencode-locale-perl libfcgi-perl libhtml-parser-perl
      libhtml-tagset-perl libhtml-template-perl libhttp-date-perl libhttp-message-perl libio-html-perl libjemalloc1 liblwp-mediatypes-perl libmariadbclient18
      libreadline5 libterm-readkey-perl libtimedate-perl liburi-perl lsof mariadb-common rsync socat
    Use 'apt autoremove' to remove them.
    The following packages will be REMOVED:
      pmm-client
    The following NEW packages will be installed:
      pmm2-client
    0 upgraded, 1 newly installed, 1 to remove and 87 not upgraded.
    Need to get 0 B/61.8 MB of archives.
    After this operation, 94.8 MB of additional disk space will be used.
    Do you want to continue? [Y/n] y
    (Reading database ... 36685 files and directories currently installed.)
    Removing pmm-client (1.17.3-1.stretch) ...
    OK, no services found.
    Uninstall complete.
    Selecting previously unselected package pmm2-client.
    (Reading database ... 36664 files and directories currently installed.)
    Preparing to unpack .../pmm2-client_2.7.0-6.stretch_amd64.deb ...
    Unpacking pmm2-client (2.7.0-6.stretch) ...
    Setting up pmm2-client (2.7.0-6.stretch) ...
    [email protected]:~# mysql -u root -p
    Enter password: 
    Welcome to the MySQL monitor.  Commands end with ; or \g.
    Your MySQL connection id is 4
    Server version: 5.7.30 MySQL Community Server (GPL)

    Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

    Oracle is a registered trademark of Oracle Corporation and/or its
    affiliates. Other names may be trademarks of their respective
    owners.

    Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

    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       | /var/lib/mysql/ip-172-30-3-190-slow.log |
    +---------------------------+-----------------------------------------+
    5 rows in set (0.00 sec)

  • steffensteffen Current User Role Supporter
    Hi Lalit,

    here are the log excerpts from my upgrade (Debian 9.11, MySQL 5.6.46):

    apt update
    apt install percona-release
    # Unpacking percona-release (1.0-19.generic) over (1.0-13.generic) ...
    apt update
    apt list --upgradable
    # pmm-client/unknown 1.17.3-1.stretch amd64 [upgradable from: 1.17.2-1.stretch]

    pmm-admin annotate "db01 replacing PMM client 1.17.2 with 2.6.1"
    apt install pmm2-client
    # The following packages will be REMOVED:
    #   pmm-client
    # The following NEW packages will be installed:
    #   pmm2-client

    # Get:1 http://repo.percona.com/percona/apt stretch/main amd64 pmm2-client amd64 2.7.0-6.stretch [61.8 MB]
    # Fetched 61.8 MB in 13s (4,677 kB/s)
    # Removing pmm-client (1.17.2-1.stretch) ...
    # OK, 3 services were removed.
    # Uninstall complete.
    # Selecting previously unselected package pmm2-client.
    # Preparing to unpack .../pmm2-client_2.7.0-6.stretch_amd64.deb ...
    # Warning: The home dir /usr/local/percona you specified already exists.
    # Adding system user `pmm-agent' (UID 114) ...
    # Adding new group `pmm-agent' (GID 119) ...
    # Adding new user `pmm-agent' (UID 114) with group `pmm-agent' ...
    # The home directory `/usr/local/percona' already exists.  Not copying from `/etc/skel'.
    # adduser: Warning: The home directory `/usr/local/percona' does not belong to the user you are currently creating.
    # Setting up pmm2-client (2.7.0-6.stretch) ...
    # Created symlink /etc/systemd/system/multi-user.target.wants/pmm-agent.service ? /lib/systemd/system/pmm-agent.service.


    After that I checked and found slow_query_log was set to 0, and it definitely was 1 before.
    I checked the Prometheus graphs: The 0 was also set on our servers running 5.7, so it's not an issue of 5.6.
    But if it's not a common problem, then it's probably not worth the effort to try and figure out what exactly in our configuration caused it.


  • lalit.choudharylalit.choudhary Percona Percona Staff Role
    Hi Steffen,
    It's very unlikely that pmm-client installation/Removal will impact mysql setting because, in order to change mysql setting dynamically without restart mysqld server, it must access mysql and do the changes.  I will see if can do some more tests.
    Thanks
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