Optimized my.cnf configuration for MySQL/MariaDB (on Ubuntu, CentOS, Almalinux etc. servers)

my.cnf

# === Optimized my.cnf configuration for MySQL/MariaDB (on Ubuntu, CentOS, Almalinux etc. servers) ===
#
# by Fotis Evangelou, developer of Engintron (engintron.com)
#
# ~ Updated September 2024 ~
#
#
# The settings provided below are a starting point for a 8-16 GB RAM server with 4-8 CPU cores.
# If you have different resources available you should adjust accordingly to save CPU, RAM & disk I/O usage.
#
# The settings marked with a specific comment or the word "UPD" (after the value)
# should be adjusted for your system by using database diagnostics tools like:
#
# https://github.com/major/MySQLTuner-perl
# or
# https://github.com/BMDan/tuning-primer.sh
#
# Run either of these scripts before optimizing your database, at least 1 hr after the optimization & finally
# at least once a day for 3 days (without restarting the database) to see how your server performs and if you need
# to re-adjust anything. The more MySQL/MariaDB runs without restarting, the more usage data it gathers, so these
# diagnostics scripts will report in mode detail how MySQL/MariaDB performs.
#
#
# IMPORTANT NOTE: If there is NO comment after a setting value, then 99,9% of the times you won't need to adjust it.
#
#
# --- THINGS TO DO AFTER YOU UPDATE MY.CNF - TROUBLESHOOTING ---
#
# If any terminal commands are mentioned, make sure you execute them as "root" user.
#
# If MySQL or MariaDB cannot start (or restart), then perform the following actions.
#
# 1. If the server had the stock database configuration and you added or updated any
#    "innodb_log_*" settings (as suggested below), then execute these commands ONLY
#    the first time you apply this configuration:
#
#    $ chown -R mysql:mysql /var/lib/mysql
#    $ service mysql restart
#
#    or use the shorthand command:
#    $ chown -R mysql:mysql /var/lib/mysql; service mysql restart
#
# 2. If the setting "bind-address" is not commented out, then make sure the file /etc/hosts is
#    properly configured. A good example of a "clean" /etc/hosts file is something like this:
#
#    127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
#    ::1       localhost localhost.localdomain localhost6 localhost6.localdomain6
#    1.2.3.4   hostname.domain.tld hostname # <-- Replace accordingly!
#
#    Finally restart the database service:
#
#    $ service mysql restart
#
# 3. If the database service cannot restart even after the first 2 steps, make sure the database data folder
#    (common for either MySQL or MariaDB) "/var/lib/mysql" is owned by the "mysql" user AND group.
#    Additionally, the folder itself can have 0751 or 0755 file permissions. To fix it, simply do this:
#    $ chown -R mysql:mysql /var/lib/mysql
#    $ chmod 0755 /var/lib/mysql
#
#    Finally restart the database service:
#
#    $ service mysql restart
#
#
# ~ FIN ~

[mysql]
port                            = 3306
socket                          = /var/run/mysqld/mysqld.sock

[mysqld]
# === Required Settings ===
basedir                         = /usr
bind_address                    = 127.0.0.1 # Change to 0.0.0.0 to allow remote connections
datadir                         = /var/lib/mysql
#default_authentication_plugin  = mysql_native_password # Enable in MySQL 8+ or MariaDB 10.6+ for backwards compatibility with common CMSs
max_allowed_packet              = 256M
max_connect_errors              = 1000000
pid_file                        = /var/run/mysqld/mysqld.pid
port                            = 3306
skip_external_locking
skip_name_resolve
socket                          = /var/run/mysqld/mysqld.sock
tmpdir                          = /tmp
user                            = mysql

# === SQL Compatibility Mode ===
# Enable for b/c with databases created in older MySQL/MariaDB versions
# (e.g. when using null dates)
#sql_mode                       = ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION,ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES
# For maximum compatibility, just use:
#sql_mode                       = ""

# === InnoDB Settings ===
default_storage_engine          = InnoDB
innodb_buffer_pool_instances    = 4     # Use 1 instance per 1GB of InnoDB pool size - max is 64
innodb_buffer_pool_size         = 4G    # Use up to 70-80% of RAM
innodb_file_per_table           = 1
innodb_flush_log_at_trx_commit  = 0
innodb_flush_method             = O_DIRECT
innodb_log_buffer_size          = 16M
innodb_log_file_size            = 1G
innodb_sort_buffer_size         = 4M    # UPD - Defines how much data is read into memory for sorting operations before writing to disk (default is 1M / max is 64M)
innodb_stats_on_metadata        = 0
#innodb_use_fdatasync           = 1     # Only (!) for MySQL v8.0.26+

#innodb_temp_data_file_path     = ibtmp1:64M:autoextend:max:20G # Control the maximum size for the ibtmp1 file
#innodb_thread_concurrency      = 4     # Optional: Set to the number of CPUs on your system (minus 1 or 2) to better
                                        # contain CPU usage. E.g. if your system has 8 CPUs, try 6 or 7 and check
                                        # the overall load produced by MySQL/MariaDB.
innodb_read_io_threads          = 64
innodb_write_io_threads         = 64
#innodb_io_capacity             = 2000  # Depends on the storage tech - use 2000 for SSD, more for NVMe
#innodb_io_capacity_max         = 4000  # Usually double the value of innodb_io_capacity

# === MyISAM Settings ===
# The following 3 options are ONLY supported by MariaDB & up to MySQL 5.7
# Do NOT un-comment on MySQL 8.x+
#query_cache_limit              = 4M    # UPD
#query_cache_size               = 64M   # UPD
#query_cache_type               = 1     # Enabled by default

key_buffer_size                 = 16M   # UPD

low_priority_updates            = 1
concurrent_insert               = 2

# === Connection Settings ===
max_connections                 = 90    # UPD - Important: high no. of connections = high RAM consumption

back_log                        = 512
thread_cache_size               = 100
thread_stack                    = 192K

interactive_timeout             = 180
wait_timeout                    = 180

# For MySQL 5.7+ only (disabled by default)
#max_execution_time             = 90000 # Set a timeout limit for SELECT statements (value in milliseconds).
                                        # This option may be useful to address aggressive crawling on large sites,
                                        # but it can also cause issues (e.g. with backups). So use with extreme caution and test!
                                        # More info at: https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_max_execution_time

# For MariaDB 10.1.1+ only (disabled by default)
#max_statement_time             = 90    # The equivalent of "max_execution_time" in MySQL 5.7+ (set above)
                                        # The variable is of type double, thus you can use subsecond timeout.
                                        # For example you can use value 0.01 for 10 milliseconds timeout.
                                        # More info at: https://mariadb.com/kb/en/aborting-statements/

# === Buffer Settings ===
# Handy tip for managing your database's RAM usage:
# The following values should be treated carefully as they are added together and then multiplied by your "max_connections" value.
# Other options will also add up to RAM consumption (e.g. tmp_table_size). So don't go switching your "join_buffer_size" to 1G, it's harmful & inefficient.
# Use one of the database diagnostics tools mentioned at the top of this file to count your database's potential total RAM usage, so you know if you are within
# reasonable limits. Remember that other services will require enough RAM to operate properly (like Apache or PHP-FPM), so set your limits wisely.
join_buffer_size                = 4M    # UPD
read_buffer_size                = 3M    # UPD
read_rnd_buffer_size            = 4M    # UPD
sort_buffer_size                = 4M    # UPD

# === Table Settings ===
# In systemd managed systems like Ubuntu 16.04+ or CentOS 7+, you need to perform an extra action for table_open_cache & open_files_limit
# to be overriden (also see comment next to open_files_limit).
# E.g. for MySQL 5.7, please check: https://dev.mysql.com/doc/refman/5.7/en/using-systemd.html
# and for MariaDB check: https://mariadb.com/kb/en/library/systemd/
table_definition_cache          = 50000 # UPD
table_open_cache                = 50000 # UPD
open_files_limit                = 60000 # UPD - This can be 2x to 3x the table_open_cache value or match the system's
                                        # open files limit usually set in /etc/sysctl.conf and /etc/security/limits.conf
                                        # In systemd managed systems this limit must also be set in:
                                        # - /etc/systemd/system/mysql.service.d/override.conf (for MySQL 5.7+ in Ubuntu) or
                                        # - /etc/systemd/system/mysqld.service.d/override.conf (for MySQL 5.7+ in CentOS) or
                                        # - /etc/systemd/system/mariadb.service.d/override.conf (for MariaDB)
                                        # otherwise changing open_files_limit will have no effect.
                                        #
                                        # To edit the right file execute:
                                        # $ systemctl edit mysql (or mysqld or mariadb)
                                        # and set "LimitNOFILE=" to something like 100000 or more (depending on your system limits for MySQL)
                                        # or use "LimitNOFILE=infinity" for MariaDB only.
                                        # Finally merge the changes with:
                                        # $ systemctl daemon-reload; systemctl restart mysql (or mysqld or mariadb)

max_heap_table_size             = 128M  # Increase to 256M, 512M or 1G if you have lots of temporary tables because of missing indices in JOINs
tmp_table_size                  = 128M  # Use same value as max_heap_table_size

# === Search Settings ===
ft_min_word_len                 = 3     # Minimum length of words to be indexed for search results

# === Binary Logging ===
disable_log_bin                 = 1     # Binary logging disabled by default
#log_bin                                # To enable binary logging, uncomment this line & only one of the following 2 lines
                                        # that corresponds to your actual MySQL/MariaDB version.
                                        # Remember to comment out the line with "disable_log_bin".
#expire_logs_days               = 1     # Keep logs for 1 day - For MySQL 5.x & MariaDB before 10.6 only
#binlog_expire_logs_seconds     = 86400 # Keep logs for 1 day (in seconds) - For MySQL 8+ & MariaDB 10.6+ only

# === Error & Slow Query Logging ===
log_error                       = /var/lib/mysql/mysql_error.log
#log_error_verbosity            = 1     # 1 for ERROR, 2 for ERROR, WARNING, 3 for ERROR, WARNING, INFORMATION (MySQL only)
                                        # Set to 1 to prevent flooding your mysql_error.log to GBs with deprecation warnings
log_queries_not_using_indexes   = 0     # Disabled on production
long_query_time                 = 5
slow_query_log                  = 0     # Disabled on production
slow_query_log_file             = /var/lib/mysql/mysql_slow.log

[mysqldump]
# Variable reference
# For MySQL 5.7+:  https://dev.mysql.com/doc/refman/5.7/en/mysqldump.html
# For MariaDB:     https://mariadb.com/kb/en/library/mysqldump/
quick
quote_names
max_allowed_packet              = 1024M

I try since weeks, but can't get cpu down.

my.cnf

# The MariaDB configuration file
#
# The MariaDB/MySQL tools read configuration files in the following order:
# 0. "/etc/mysql/my.cnf" symlinks to this file, reason why all the rest is read.
# 1. "/etc/mysql/mariadb.cnf" (this file) to set global defaults,
# 2. "/etc/mysql/conf.d/*.cnf" to set global options.
# 3. "/etc/mysql/mariadb.conf.d/*.cnf" to set MariaDB-only options.
# 4. "~/.my.cnf" to set user-specific options.
#
# If the same option is defined multiple times, the last one will apply.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# If you are new to MariaDB, check out https://mariadb.com/kb/en/basic-mariadb-articles/

#
# This group is read both by the client and the server
# use it for options that affect everything
#
[client-server]
# Port or socket location where to connect
# port = 3306
socket = /run/mysqld/mysqld.sock

# Import all .cnf files from configuration directory
!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mariadb.conf.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

performance_schema	= ON

wait_timeout = 31536000
max_allowed_packet=500M
max_connect_errors = 100000

table-definition-cache=10000
table_open_cache=1000

open_files_limit = 65536

max_heap_table_size             = 512M  # Increase to 256M or 512M if you have lots of temporary tables because of missing indices in JOINs
tmp_table_size                  = 512M

max_write_lock_count=16
join_buffer_size				= 256K
read_buffer_size                = 128K    # UPD
read_rnd_buffer_size            = 2M    # UPD
sort_buffer_size                = 2M    # UPD

low_priority_updates=1
concurrent_insert=ALWAYS

query_cache_type		= 0
query_cache_size		= 0
#query_cache_limit		= OFF
# for more write intensive setups, set to DEMAND or OFF

key_buffer_size = 50M
max_connections=60
thread_cache_size=100
thread_stack = 192K
log_warnings=2


innodb_thread_concurrency=0
innodb_buffer_pool_size=5G
innodb_buffer_pool_instances = 4
innodb_flush_log_at_trx_commit=0
innodb_flush_method=O_DIRECT

innodb_log_buffer_size=16M
innodb_log_file_size=1G
innodb_io_capacity=10000
innodb_read_io_threads = 64
innodb_write_io_threads = 64
innodb_change_buffer_max_size=10
innodb_sort_buffer_size=4M

wait_timeout=80


log_error                       = /var/lib/mysql/mysql_error.log
log_queries_not_using_indexes   = ON     # Disabled on production
long_query_time                 = 1
slow_query_log                  = 1     # Disabled on production
log_queries_not_using_indexes	= ON
slow_query_log_file             = /var/lib/mysql/mysql_slow.log
log_slow_verbosity	= query_plan

For me I had to comment these lines out:

#pid_file                        = /var/run/mysqld/mysqld.pid
#socket                          = /var/run/mysqld/mysqld.sock

Then it started normally and I was able to access through phpmyadmin :)

Also for anyone using AlmaLinux, the my.cnf is located in:
etc/my.cnf

And if you're using MariaDB, I recommend re-adding this:

#
# include *.cnf from the config directory
#
!includedir /etc/my.cnf.d