7.1.1 Configuring the Server

The MySQL server, mysqld, has many command options and system variables that can be set at startup to configure its operation. To determine the default command option and system variable values used by the server, execute this command:

$> mysqld --verbose --help

The command produces a list of all mysqld options and configurable system variables. Its output includes the default option and variable values and looks something like this:

abort-slave-event-count           0
allow-suspicious-udfs             FALSE
archive                           ON
auto-increment-increment          1
auto-increment-offset             1
autocommit                        TRUE
automatic-sp-privileges           TRUE
avoid-temporal-upgrade            FALSE
back-log                          80
basedir                           /home/jon/bin/mysql-8.0/
...
tmpdir                            /tmp
transaction-alloc-block-size      8192
transaction-isolation             REPEATABLE-READ
transaction-prealloc-size         4096
transaction-read-only             FALSE
transaction-write-set-extraction  XXHASH64
updatable-views-with-limit        YES
validate-user-plugins             TRUE
verbose                           TRUE
wait-timeout                      28800

To see the current system variable values actually used by the server as it runs, connect to it and execute this statement:

mysql> SHOW VARIABLES;

To see some statistical and status indicators for a running server, execute this statement:

mysql> SHOW STATUS;

System variable and status information also is available using the mysqladmin command:

$> mysqladmin variables
$> mysqladmin extended-status

For a full description of all command options, system variables, and status variables, see these sections:

• Section 7.1.7, “Server Command Options”

• Section 7.1.8, “Server System Variables”

• Section 7.1.10, “Server Status Variables”

More detailed monitoring information is available from the Performance Schema; see Chapter 29, MySQL Performance Schema. In addition, the MySQL sys schema is a set of objects that provides convenient access to data collected by the Performance Schema; see Chapter 30, MySQL sys Schema.

If you specify an option on the command line for mysqld or mysqld_safe, it remains in effect only for that invocation of the server. To use the option every time the server runs, put it in an option file. See Section 6.2.2.2, “Using Option Files”.