I upgrade some month ago from Ubuntu 18.04 to 20.04. So MySQL upgrade from 5.7.33 to 8.0.23.
I notice after the upgrade that MySQL is slow to start.
2021-02-24T09:20:16.972632Z 0 [System] [MY-013172] [Server] Received SHUTDOWN from user <via user signal>. Shutting down mysqld (Version: 8.0.23-0ubuntu0.20.04.1).
2021-02-24T09:23:19.459483Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.23-0ubuntu0.20.04.1) (Ubuntu).
2021-02-24T09:28:43.738171Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.23-0ubuntu0.20.04.1) starting as process 999
2021-02-24T09:28:44.973719Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2021-02-24T09:33:02.352311Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2021-02-24T09:33:06.424798Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060, socket: /var/run/mysqld/mysqlx.sock
2021-02-24T09:33:07.646778Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2021-02-24T09:33:07.647106Z 0 [System] [MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
2021-02-24T09:33:08.295842Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.23-0ubuntu0.20.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu)
The slowdown seems to come from the "InnoDB initialization".
The MySQL contains 70 databases (Wordpress) for development project and are not actively used.
I also notice this slowdown on 3 other servers. (but not as much and they contains less databases.)
Due to this slowdown, websites display "database connection" error during Innodb initialization.
What causes exactly this slowdown ? Is there any parameter to speed up the process ?
Edit : Actual configuration
#
# The MySQL database server configuration file.
#
# 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.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
Here is entries for some specific programs
The following values assume you have at least 32M ram
[mysqld]
* Basic Settings
user = mysql
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
port = 3306
basedir = /usr
datadir = /var/lib/mysql
If MySQL is running as a replication slave, this should be
changed. Ref https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_tmpdir
tmpdir = /tmp
Instead of skip-networking the default is now to listen only on
localhost which is more compatible and is not less secure.
bind-address = 127.0.0.1
* Fine Tuning
key_buffer_size = 16M
max_allowed_packet = 64M
thread_stack = 256K
thread_cache_size = -1
This replaces the startup script and checks MyISAM tables if needed
the first time they are touched
myisam-recover-options = BACKUP
max_connections = 151
table_open_cache = 4000
* Logging and Replication
Both location gets rotated by the cronjob.
Log all queries
Be aware that this log type is a performance killer.
general_log_file = /var/log/mysql/query.log
general_log = 1
Error log - should be very few entries.
log_error = /var/log/mysql/error.log
Here you can see queries with especially long duration
slow_query_log = 1
slow_query_log_file = /var/log/mysql/mysql-slow.log
long_query_time = 2
log-queries-not-using-indexes
The following can be used as easy to replay backup logs or for replication.
note: if you are setting up a replication slave, see README.Debian about
other settings you may need to change.
server-id = 1
log_bin = /var/log/mysql/mysql-bin.log
binlog_expire_logs_seconds = 2592000
max_binlog_size = 100M
binlog_do_db = include_database_name
binlog_ignore_db = include_database_name
skip-name-resolve
table_open_cache = 4000
join_buffer_size = 8M
tmp_table_size = 64M
key_buffer_size = 48M
max_heap_table_size = 64M
innodb_buffer_pool_size = 1500M
innodb_buffer_pool_instances = 1
innodb_log_file_size = 190M
