maria-discuss team mailing list archive

[Gordan Bobic <gordan.bobic@xxxxxxxxx>]

A lot of MySQL Tuner's advice is based on extensive misconceptions and
questionable understanding of MySQL internals. Realistically - the
best option is to just pretend it doesn't exist.
But since you asked:

    join_buffer_size (> 5.0M, or always use indexes with JOINs)

It is spectacularly bad advice to suggest off hand that increasing the
join buffer size is a good idea.
If you genuinely do find that you need to increase it, you almost
certainly have bigger problems that would be better addressed by
improving your queries and indexes.

    innodb_log_file_size should be (=16M) if possible, so InnoDB total
log files size equals 25% of buffer pool size.

I have no idea where this notion that innodb_log_file_size is in any
way related to the buffer pool size, but it is completely
non-sensical. The two are not in any way related, and each needs to be
configured independently in a way that is appropriate to the server's
workload.

Bottom line: uninstall MySQL Tuner and forget it ever existed. At best
it will mislead you. At worst it will completely cripple the server.


On Wed, Jan 18, 2023 at 2:27 PM Dragos Pacher <dragosrp@xxxxxxxxx> wrote:
>
> Hello,
>
> I am looking for an expert opinion on MySQLTuner-perl recommendations and usefulness in my specific case of MariaDB 10.3.35
> with Plesk Web Host Edition 18.0.49 Update #2 - with a somehow default installation: one demo site added + some popular
> components in default state idling - on Rocky Linux 8.7 kernel 4.18.0-425.10.1.el8_7.x86_64.
>
> What are your opinions on the recommendations below? My machine is a VirtualBox 7.0.4 one(on Windows 11 22H2 build 22621.1105)
> with slower Seagate Barracuda PRO disks (non RAID), 8 GB RAM, processor Ryzen 7 3700x(all cores assigned). This was meant
> just for testing but I am trying to extrapolate some of the results here for a production environment with generous
> hardware(over 48 GB RAM and newer generation CPUs, NVME/RAIDs). The only way (as of now) for Plesk to work is by coexisting on the
> same machine with the database server - please take this into consideration.
>
> Please see the results below after ~15-24h of Plesk idling on the machine. Also please let me know if you need more data
> from my side or if I should enable something and rerun a specific test, I can provide detailed statistics if needed. I am
> really looking forward on how to make this database a bit faster if possible(without enabling really dangerous options).
> Thank you.
>
> [root@pensive-aryabhata ~]# cat /etc/my.cnf
> #
> # This group is read both both by the client and the server
> # use it for options that affect everything
> #
> [client-server]
>
> #
> # include all files from the config directory
> #
> !includedir /etc/my.cnf.d
>
> [mysqld]
> sql_mode=ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
> bind-address = ::ffff:127.0.0.1
> local-infile=0
>
> join_buffer_size                = 5M # I changed this from 3 to 5 24h before running the MySQLTuner
>
> [root@pensive-aryabhata ~]# sysctl -a | grep swapp
> vm.force_cgroup_v2_swappiness = 0
> vm.swappiness = 5
>
> [root@pensive-aryabhata ~]# perl mysqltuner.pl --host 127.0.0.1
>  >>  MySQLTuner 2.0.10
>          * Jean-Marie Renouard <jmrenouard@xxxxxxxxx>
>          * Major Hayden <major@xxxxxxxx>
>  >>  Bug reports, feature requests, and downloads at http://mysqltuner.pl/
>  >>  Run with '--help' for additional options and output filtering
>
> [--] Skipped version check for MySQLTuner script
> [--] Performing tests on 127.0.0.1:3306
> [OK] Currently running supported MySQL version 10.3.35-MariaDB
> [OK] Operating on 64-bit architecture
>
> -------- Log file Recommendations ------------------------------------------------------------------
> [OK] Log file /var/log/mariadb/mariadb.log exists
> [--] Log file: /var/log/mariadb/mariadb.log (13K)
> [OK] Log file /var/log/mariadb/mariadb.log is not empty
> [OK] Log file /var/log/mariadb/mariadb.log is smaller than 32 Mb
> [OK] Log file /var/log/mariadb/mariadb.log is readable.
> [!!] /var/log/mariadb/mariadb.log contains 15 warning(s).
> [!!] /var/log/mariadb/mariadb.log contains 2 error(s).
> [--] 5 start(s) detected in /var/log/mariadb/mariadb.log
> [--] 1) 2023-01-17 23:36:33 0 [Note] /usr/libexec/mysqld: ready for connections.
> [--] 2) 2023-01-17 23:36:20 0 [Note] /usr/libexec/mysqld: ready for connections.
> [--] 3) 2023-01-17 23:23:33 0 [Note] /usr/libexec/mysqld: ready for connections.
> [--] 4) 2023-01-17 18:18:58 0 [Note] /usr/libexec/mysqld: ready for connections.
> [--] 5) 2023-01-17 18:18:24 0 [Note] /usr/libexec/mysqld: ready for connections.
> [--] 4 shutdown(s) detected in /var/log/mariadb/mariadb.log
> [--] 1) 2023-01-17 23:36:29 0 [Note] /usr/libexec/mysqld: Shutdown complete
> [--] 2) 2023-01-17 23:36:16 0 [Note] /usr/libexec/mysqld: Shutdown complete
> [--] 3) 2023-01-17 23:20:59 0 [Note] /usr/libexec/mysqld: Shutdown complete
> [--] 4) 2023-01-17 18:18:50 0 [Note] /usr/libexec/mysqld: Shutdown complete
>
> -------- Storage Engine Statistics -----------------------------------------------------------------
> [--] Status: +ARCHIVE +Aria +BLACKHOLE +CSV +FEDERATED +InnoDB +MEMORY +MRG_MyISAM +MyISAM +PERFORMANCE_SCHEMA +SEQUENCE
> [--] Data in InnoDB tables: 8.2M (Tables: 267)
> [OK] Total fragmented tables: 0
>
> -------- Analysis Performance Metrics --------------------------------------------------------------
> [--] innodb_stats_on_metadata: OFF
> [OK] No stat updates during querying INFORMATION_SCHEMA.
>
> -------- Views Metrics -----------------------------------------------------------------------------
>
> -------- Triggers Metrics --------------------------------------------------------------------------
>
> -------- Routines Metrics --------------------------------------------------------------------------
>
> -------- Security Recommendations ------------------------------------------------------------------
> [OK] There are no anonymous accounts for any database users
> [OK] All database users have passwords assigned
> [!!] There is no basic password file list!
>
> -------- CVE Security Recommendations --------------------------------------------------------------
> [--] Skipped due to --cvefile option undefined
>
> -------- Performance Metrics -----------------------------------------------------------------------
> [--] Up for: 13h 39m 22s (45K q [0.920 qps], 1K conn, TX: 38M, RX: 3M)
> [--] Reads / Writes: 86% / 14%
> [--] Binary logging is disabled
> [--] Physical Memory     : 7.6G
> [--] Max MySQL memory    : 3.9G
> [--] Other process memory: 0B
> [--] Total buffers: 417.0M global + 23.7M per thread (151 max threads)
> [--] Performance_schema Max memory usage: 0B
> [--] Galera GCache Max memory usage: 0B
> [OK] Maximum reached memory usage: 724.6M (9.33% of installed RAM)
> [OK] Maximum possible memory usage: 3.9G (51.40% of installed RAM)
> [OK] Overall possible memory usage with other process is compatible with memory available
> [OK] Slow queries: 0% (0/45K)
> [OK] Highest usage of available connections: 8% (13/151)
> [OK] Aborted connections: 0.30% (3/1012)
> [!!] Name resolution is active: a reverse name resolution is made for each new connection which can reduce performance
> [OK] Query cache is disabled by default due to mutex contention on multiprocessor machines.
> [OK] Sorts requiring temporary tables: 0% (0 temp sorts / 306 sorts)
> [!!] Joins performed without indexes: 228
> [!!] Temporary tables created on disk: 90% (8K on disk / 9K total)
> [OK] Thread cache hit rate: 86% (140 created / 1K connections)
> [OK] Table cache hit rate: 98% (42K hits / 43K requests)
> [!!] table_definition_cache (400) is less than number of tables (428)
> [OK] Open file limit used: 0% (84/32K)
> [OK] Table locks acquired immediately: 100% (48 immediate / 48 locks)
>
> -------- Performance schema ------------------------------------------------------------------------
> [!!] Performance_schema should be activated.
> [--] Sys schema is not installed.
>
> -------- ThreadPool Metrics ------------------------------------------------------------------------
> [--] ThreadPool stat is disabled.
>
> -------- MyISAM Metrics ----------------------------------------------------------------------------
> [!!] Key buffer used: 18.3% (23.4M used / 128.0M cache)
> [OK] Key buffer size / total MyISAM indexes: 128.0M/123.0K
> [!!] Read Key buffer hit rate: 73.3% (75 cached / 20 reads)
>
> -------- InnoDB Metrics ----------------------------------------------------------------------------
> [--] InnoDB is enabled.
> [--] InnoDB Thread Concurrency: 0
> [OK] InnoDB File per table is activated
> [OK] InnoDB buffer pool / data size: 128.0M / 8.2M
> [!!] Ratio InnoDB log file size / InnoDB Buffer pool size (75%): 48.0M * 2 / 128.0M should be equal to 25%
> [OK] InnoDB buffer pool instances: 1
> [--] Number of InnoDB Buffer Pool Chunk: 1 for 1 Buffer Pool Instance(s)
> [OK] Innodb_buffer_pool_size aligned with Innodb_buffer_pool_chunk_size & Innodb_buffer_pool_instances
> [OK] InnoDB Read buffer efficiency: 99.08% (182560 hits / 184256 total)
> [!!] InnoDB Write Log efficiency: 11.48% (114 hits / 993 total)
> [OK] InnoDB log waits: 0.00% (0 waits / 1107 writes)
>
> -------- Aria Metrics ------------------------------------------------------------------------------
> [--] Aria Storage Engine is enabled.
> [OK] Aria pagecache size / total Aria indexes: 128.0M/0B
> [!!] Aria pagecache hit rate: 91.0% (95K cached / 8K reads)
>
> -------- TokuDB Metrics ----------------------------------------------------------------------------
> [--] TokuDB is disabled.
>
> -------- XtraDB Metrics ----------------------------------------------------------------------------
> [--] XtraDB is disabled.
>
> -------- Galera Metrics ----------------------------------------------------------------------------
> [--] Galera is disabled.
>
> -------- Replication Metrics -----------------------------------------------------------------------
> [--] Galera Synchronous replication: NO
> [--] No replication slave(s) for this server.
> [--] Binlog format: MIXED
> [--] XA support enabled: ON
> [--] Semi synchronous replication Master: OFF
> [--] Semi synchronous replication Slave: OFF
> [--] This is a standalone server
>
> -------- Recommendations ---------------------------------------------------------------------------
> General recommendations:
>     Check warning line(s) in /var/log/mariadb/mariadb.log file
>     Check error line(s) in /var/log/mariadb/mariadb.log file
>     MySQL was started within the last 24 hours: recommendations may be inaccurate
>     Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1
>     We will suggest raising the 'join_buffer_size' until JOINs not using indexes are found.
>              See https://dev.mysql.com/doc/internals/en/join-buffer-size.html
>              (specially the conclusions at the bottom of the page).
>     When making adjustments, make tmp_table_size/max_heap_table_size equal
>     Reduce your SELECT DISTINCT queries which have no LIMIT clause
>     Performance schema should be activated for better diagnostics
>     Consider installing Sys schema from https://github.com/mysql/mysql-sys for MySQL
>     Before changing innodb_log_file_size and/or innodb_log_files_in_group read this: https://bit.ly/2TcGgtU
> Variables to adjust:
>     skip-name-resolve=1
>     join_buffer_size (> 5.0M, or always use indexes with JOINs)
>     tmp_table_size (> 16M)
>     max_heap_table_size (> 16M)
>     table_definition_cache (400) > 428 or -1 (autosizing if supported)
>     performance_schema=ON
>     key_buffer_size (~ 24M)
>     innodb_log_file_size should be (=16M) if possible, so InnoDB total log files size equals 25% of buffer pool size.
>
> # end of MySQL Tuner-perl script #1
>
> # more details
> [root@pensive-aryabhata ~]# perl mysqltuner.pl --buffers --dbstat --idxstat --sysstat --pfstat --tbstat
> #
> # skipped part as the output was too big
> #
> -------- Views Metrics -----------------------------------------------------------------------------
>
> -------- Triggers Metrics --------------------------------------------------------------------------
>
> -------- Routines Metrics --------------------------------------------------------------------------
>
> -------- Security Recommendations ------------------------------------------------------------------
> [OK] There are no anonymous accounts for any database users
> [OK] All database users have passwords assigned
> [!!] There is no basic password file list!
>
> -------- CVE Security Recommendations --------------------------------------------------------------
> [--] Skipped due to --cvefile option undefined
>
> -------- Performance Metrics -----------------------------------------------------------------------
> [--] Up for: 13m 5s (3K q [4.741 qps], 1K conn, TX: 1M, RX: 549K)
> [--] Reads / Writes: 97% / 3%
> [--] Binary logging is disabled
> [--] Physical Memory     : 7.6G
> [--] Max MySQL memory    : 3.9G
> [--] Other process memory: 1.1G
> [--] Total buffers: 417.0M global + 23.7M per thread (151 max threads)
> [--] Performance_schema Max memory usage: 0B
> [--] Galera GCache Max memory usage: 0B
> [--] Global Buffers
> [--]  +-- Key Buffer: 128.0M
> [--]  +-- Max Tmp Table: 16.0M
> [--] Query Cache Buffers
> [--]  +-- Query Cache: OFF - DISABLED
> [--]  +-- Query Cache Size: 1.0M
> [--] Per Thread Buffers
> [--]  +-- Read Buffer: 128.0K
> [--]  +-- Read RND Buffer: 256.0K
> [--]  +-- Sort Buffer: 2.0M
> [--]  +-- Thread stack: 292.0K
> [--]  +-- Join Buffer: 5.0M
> [OK] Maximum reached memory usage: 535.3M (6.90% of installed RAM)
> [OK] Maximum possible memory usage: 3.9G (51.40% of installed RAM)
> [OK] Overall possible memory usage with other process is compatible with memory available
> [OK] Slow queries: 0% (0/3K)
> [OK] Highest usage of available connections: 3% (5/151)
> [OK] Aborted connections: 0.00% (0/1594)
> [!!] Name resolution is active: a reverse name resolution is made for each new connection which can reduce performance
> [OK] Query cache is disabled by default due to mutex contention on multiprocessor machines.
> [OK] Sorts requiring temporary tables: 0% (0 temp sorts / 93 sorts)
> [!!] Joins performed without indexes: 4
> [!!] Temporary tables created on disk: 73% (1K on disk / 1K total)
> [OK] Thread cache hit rate: 99% (5 created / 1K connections)
> [OK] Table cache hit rate: 89% (3K hits / 3K requests)
> [!!] table_definition_cache (400) is less than number of tables (428)
> [OK] Open file limit used: 0% (59/32K)
> [OK] Table locks acquired immediately: 100% (18 immediate / 18 locks)
>
> -------- Performance schema ------------------------------------------------------------------------
> [!!] Performance_schema should be activated.
> [--] Sys schema is not installed.
>
> -------- ThreadPool Metrics ------------------------------------------------------------------------
> [--] ThreadPool stat is disabled.
>
> -------- MyISAM Metrics ----------------------------------------------------------------------------
> [!!] Key buffer used: 18.2% (23.3M used / 128.0M cache)
> [OK] Key buffer size / total MyISAM indexes: 128.0M/123.0K
>
> -------- InnoDB Metrics ----------------------------------------------------------------------------
> [--] InnoDB is enabled.
> [--] InnoDB Buffers
> [--]  +-- InnoDB Buffer Pool: 128.0M
> [--]  +-- InnoDB Buffer Pool Instances: 1
> [--]  +-- InnoDB Buffer Pool Chunk Size: 128.0M
> [--]  +-- InnoDB Log File Size: 48.0M
> [--]  +-- InnoDB Log File In Group: 2
> [--]  +-- InnoDB Total Log File Size: 96.0M(75 % of buffer pool)
> [--]  +-- InnoDB Log Buffer: 16.0M
> [--]  +-- InnoDB Log Buffer Free: 6.2K
> [--]  +-- InnoDB Log Buffer Used: 8.0K
> [--] InnoDB Thread Concurrency: 0
> [OK] InnoDB File per table is activated
> [OK] InnoDB buffer pool / data size: 128.0M / 8.2M
> [!!] Ratio InnoDB log file size / InnoDB Buffer pool size (75%): 48.0M * 2 / 128.0M should be equal to 25%
> [OK] InnoDB buffer pool instances: 1
> [--] Number of InnoDB Buffer Pool Chunk: 1 for 1 Buffer Pool Instance(s)
> [OK] Innodb_buffer_pool_size aligned with Innodb_buffer_pool_chunk_size & Innodb_buffer_pool_instances
> [!!] InnoDB Read buffer efficiency: 83.63% (8790 hits / 10511 total)
> [!!] InnoDB Write Log efficiency: 154.55% (17 hits / 11 total)
> [OK] InnoDB log waits: 0.00% (0 waits / 28 writes)
>
> -------- Aria Metrics ------------------------------------------------------------------------------
> [--] Aria Storage Engine is enabled.
> [OK] Aria pagecache size / total Aria indexes: 128.0M/0B
> [OK] Aria pagecache hit rate: 95.4% (29K cached / 1K reads)
>
> -------- TokuDB Metrics ----------------------------------------------------------------------------
> [--] TokuDB is disabled.
>
> -------- XtraDB Metrics ----------------------------------------------------------------------------
> [--] XtraDB is disabled.
>
> -------- Galera Metrics ----------------------------------------------------------------------------
> [--] Galera is disabled.
>
> -------- Replication Metrics -----------------------------------------------------------------------
> [--] Galera Synchronous replication: NO
> [--] No replication slave(s) for this server.
> [--] Binlog format: MIXED
> [--] XA support enabled: ON
> [--] Semi synchronous replication Master: OFF
> [--] Semi synchronous replication Slave: OFF
> [--] This is a standalone server
>
> -------- Recommendations ---------------------------------------------------------------------------
> General recommendations:
>     Consider stopping or dedicate server for additional process other than mysqld.
>     Check warning line(s) in /var/log/mariadb/mariadb.log file
>     Check error line(s) in /var/log/mariadb/mariadb.log file
>     Limit charset for column to one charset if possible for psa database.
>     Limit collations for column to one collation if possible for psa database.
>     Limit collations for column to one collation if possible for phpmyadmin database.
>     Check all table collations are identical for all tables in roundcubemail database.
>     Limit collations for column to one collation if possible for roundcubemail database.
>     Limit charset for column to one charset if possible for apsc database.
>     Limit collations for column to one collation if possible for apsc database.
>     Add at least a primary key on table psa.SchemaVersions
>     Add at least a primary key on table psa.suspend_handler_history
>     Add at least a primary key on table psa.WebsitesDiagnosticDomains
>     MySQL was started within the last 24 hours: recommendations may be inaccurate
>     Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1
>     We will suggest raising the 'join_buffer_size' until JOINs not using indexes are found.
>              See https://dev.mysql.com/doc/internals/en/join-buffer-size.html
>              (specially the conclusions at the bottom of the page).
>     When making adjustments, make tmp_table_size/max_heap_table_size equal
>     Reduce your SELECT DISTINCT queries which have no LIMIT clause
>     Performance schema should be activated for better diagnostics
>     Consider installing Sys schema from https://github.com/mysql/mysql-sys for MySQL
>     Before changing innodb_log_file_size and/or innodb_log_files_in_group read this: https://bit.ly/2TcGgtU
> Variables to adjust:
>     DON'T APPLY SETTINGS BECAUSE THERE ARE TOO MANY PROCESSES RUNNING ON THIS SERVER. OOM KILL CAN OCCUR!
>     skip-name-resolve=1
>     join_buffer_size (> 5.0M, or always use indexes with JOINs)
>     tmp_table_size (> 16M)
>     max_heap_table_size (> 16M)
>     table_definition_cache (400) > 428 or -1 (autosizing if supported)
>     performance_schema=ON
>     key_buffer_size (~ 24M)
>     innodb_log_file_size should be (=16M) if possible, so InnoDB total log files size equals 25% of buffer pool size.
>
> # end of MySQLTuner command #2
>
> ###################################################
> # here we can see the databases and count number of tables if this matters
>
> MariaDB [psa]> show databases;
> +--------------------+
> | Database           |
> +--------------------+
> | apsc               |
> | information_schema |
> | mysql              |
> | performance_schema |
> | phpmyadmin         |
> | psa                |
> | roundcubemail      |
> +--------------------+
> 7 rows in set (0.001 sec)
>
> MariaDB [psa]> SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = 'apsc';
> +----------+
> | COUNT(*) |
> +----------+
> |       23 |
> +----------+
> 1 row in set (0.003 sec)
>
> MariaDB [psa]> SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = 'mysql';
> +----------+
> | COUNT(*) |
> +----------+
> |       31 |
> +----------+
> 1 row in set (0.001 sec)
>
> MariaDB [psa]> SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = 'phpmyadmin';
> +----------+
> | COUNT(*) |
> +----------+
> |       19 |
> +----------+
> 1 row in set (0.001 sec)
>
> MariaDB [psa]> SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = 'psa';
> +----------+
> | COUNT(*) |
> +----------+
> |      208 |
> +----------+
> 1 row in set (0.001 sec)
>
> MariaDB [psa]> SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = 'roundcubemail';
> +----------+
> | COUNT(*) |
> +----------+
> |       17 |
> +----------+
> 1 row in set (0.001 sec)
>
>
> # Thank you,
>
> Dragos
>
>
>
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