MySQL 8 sample config (my.cnf example) and tuning.

With the release of MySQL 8 I wanted to paste my tuned my.cnf (MySQL configuration file) for discussion, suggestions, and questions. To get the most out of your MySQL 8 installation, you will need to configure it correctly and tune the settings for your specific use case. In this blog post, we will discuss my sample MySQL 8 configuration file and some tips for tuning the settings for optimal performance.

The MySQL configuration file, also known as my.cnf, is a text file that contains configuration settings for your MySQL installation. The file is usually located in the MySQL installation directory, and it can be edited with a text editor.

With the launch of this blog’s tech forums, I’m hoping that the performance tuning tips that emerge will be from all of us who manage MySQL databases. Recommendations are continued in the comments section at the end of this article.

Screenshot from btop showing MySQL 8 memory and CPU usage.

Sample MySQL 8 Config

The my.cnf configuration file shared below is from a standalone MySQL 8 server that was recently separated from a web server. It consistently performs around 9,000 queries per second (QPS) on average.

However, there are occasional spikes where the QPS increases to around 40,000 and lasts for a few days. These events occur roughly 5 to 10 times a year.

Some of the notable config lines are:

max_conections

max_conections is set for the 5 to 10 times per year peak connections,

thread_cache_size

thread_cache_size is set somewhere in between normal traffic and those peak days.

innodb_buffer_pool_instances

innodb_buffer_pool_instances is set to 48 because innodb_dedicated_server automatically sets innodb_buffer_pool_size to 48 GB. See the chart below:

Source: https://dev.mysql.com/doc/refman/8.0/en/innodb-dedicated-server.html

MySQL buffers

For read_buffer_size, join_buffer_size, sort_buffer_size and read_rnd_buffer_size, please read this important tuning article.

Misc.

performance-schema, read Performance Schema Benchmarks: OLTP RW.

disable-log-bin, read How Binary Logs Affect MySQL 8.0 Performance.

Paste of MySQL 8 my.cnf

[mysqld]
disable-log-bin = 1
skip-name-resolve = 1
performance-schema = 0
local-infile = 0
mysqlx = 0
bind-address = [IPs removed]
open_files_limit = 200000
max_allowed_packet = 256M
sql_mode = "STRICT_TRANS_TABLES,ONLY_FULL_GROUP_BY,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION"

innodb_dedicated_server = 1
innodb_buffer_pool_instances = 48
innodb_log_buffer_size = 64M
innodb_read_io_threads = 12
innodb_write_io_threads = 12
innodb_stats_on_metadata = 0
innodb_file_per_table = 1

max_connections = 500
thread_cache_size = 128
table_definition_cache = 65536
table_open_cache = 65536

wait_timeout = 10
connect_timeout = 5
interactive_timeout = 30

tmp_table_size = 128M
max_heap_table_size = 128M

read_buffer_size = 256K
join_buffer_size = 512K
sort_buffer_size = 512K
read_rnd_buffer_size = 512K

slow-query-log = 1
long_query_time = 2
slow_query_log_file = /var/log/mysql_slow_query.log
log-error = /var/log/mysql/db.[removed].com.err

Have questions or suggestions? Add your comment at the end of this article.

MySQL server ‘status’

This is the output of MySQL status for the above MySQL server:

mysql> status
--------------
Server version: 8.0.30 MySQL Community Server - GPL
Uptime: 37 days 5 hours 39 min 39 sec
Threads: 8 Questions: 31068214993 Slow queries: 0 Opens: 36331 
Flush tables: 1 Open tables: 36024 Queries per second avg: 9656.974

Continue reading MySQL performance-related guides

• MySQL Database Performance: Avoid this common mistake.
• Tuning MySQL my.cnf? Avoid this common pitfall!
• MySQL Performance Tuning: Tips, Scripts and Tools.
• MySQL Performance: Stop hoarding. Drop unused MySQL databases.
• Could not increase number of max_open_files to more than… (Solution).
• “MySQL server has gone away” error – Solution(s).
• Linux server performance: Is disk I/O slowing your application?