The variables_info
table shows,
for each system variable, the source from which it was most
recently set, and its range of values.
The variables_info
table has
these columns:
VARIABLE_NAME
The variable name.
VARIABLE_SOURCE
The source from which the variable was most recently set:
COMMAND_LINE
The variable was set on the command line.
COMPILED
The variable has its compiled-in default value.
COMPILED
is the value used for variables not set any other way.DYNAMIC
The variable was set at runtime. This includes variables set within files specified using the
init_file
system variable.EXPLICIT
The variable was set from an option file named with the
--defaults-file
option.EXTRA
The variable was set from an option file named with the
--defaults-extra-file
option.GLOBAL
The variable was set from a global option file. This includes option files not covered by
EXPLICIT
,EXTRA
,LOGIN
,PERSISTED
,SERVER
, orUSER
.LOGIN
The variable was set from a user-specific login path file (
~/.mylogin.cnf
).PERSISTED
The variable was set from a server-specific
mysqld-auto.cnf
option file. No row has this value if the server was started withpersisted_globals_load
disabled.SERVER
The variable was set from a server-specific
option file. For details about how$MYSQL_HOME
/my.cnfMYSQL_HOME
is set, see Section 6.2.2.2, “Using Option Files”.USER
The variable was set from a user-specific
~/.my.cnf
option file.
VARIABLE_PATH
If the variable was set from an option file,
VARIABLE_PATH
is the path name of that file. Otherwise, the value is the empty string.MIN_VALUE
The minimum permitted value for the variable. For a variable whose type is not numeric, this is always 0.
MAX_VALUE
The maximum permitted value for the variable. For a variable whose type is not numeric, this is always 0.
SET_TIME
The time at which the variable was most recently set. The default is the time at which the server initialized global system variables during startup.
SET_USER
,SET_HOST
The user name and host name of the client user that most recently set the variable. If a client connects as
user17
from hosthost34.example.com
using the account'user17'@'%.example.com
,SET_USER
andSET_HOST
areuser17
andhost34.example.com
, respectively. For proxy user connections, these values correspond to the external (proxy) user, not the proxied user against which privilege checking is performed. The default for each column is the empty string, indicating that the variable has not been set since server startup.
The variables_info
table has no
indexes.
TRUNCATE TABLE
is not permitted
for the variables_info
table.
If a variable with a VARIABLE_SOURCE
value
other than DYNAMIC
is set at runtime,
VARIABLE_SOURCE
becomes
DYNAMIC
and
VARIABLE_PATH
becomes the empty string.
A system variable that has only a session value (such as
debug_sync
) cannot be set at
startup or persisted. For session-only system variables,
VARIABLE_SOURCE
can be only
COMPILED
or DYNAMIC
.
If a system variable has an unexpected
VARIABLE_SOURCE
value, consider your server
startup method. For example, mysqld_safe
reads option files and passes certain options it finds there
as part of the command line that it uses to start
mysqld. Consequently, some system variables
that you set in option files might display in
variables_info
as
COMMAND_LINE
, rather than as
GLOBAL
or SERVER
as you
might otherwise expect.
Some sample queries that use the
variables_info
table, with
representative output:
Display variables set on the command line:
mysql> SELECT VARIABLE_NAME FROM performance_schema.variables_info WHERE VARIABLE_SOURCE = 'COMMAND_LINE' ORDER BY VARIABLE_NAME; +---------------+ | VARIABLE_NAME | +---------------+ | basedir | | datadir | | log_error | | pid_file | | plugin_dir | | port | +---------------+
Display variables set from persistent storage:
mysql> SELECT VARIABLE_NAME FROM performance_schema.variables_info WHERE VARIABLE_SOURCE = 'PERSISTED' ORDER BY VARIABLE_NAME; +--------------------------+ | VARIABLE_NAME | +--------------------------+ | event_scheduler | | max_connections | | validate_password.policy | +--------------------------+
Join
variables_info
with theglobal_variables
table to display the current values of persisted variables, together with their range of values:mysql> SELECT VI.VARIABLE_NAME, GV.VARIABLE_VALUE, VI.MIN_VALUE,VI.MAX_VALUE FROM performance_schema.variables_info AS VI INNER JOIN performance_schema.global_variables AS GV USING(VARIABLE_NAME) WHERE VI.VARIABLE_SOURCE = 'PERSISTED' ORDER BY VARIABLE_NAME; +--------------------------+----------------+-----------+-----------+ | VARIABLE_NAME | VARIABLE_VALUE | MIN_VALUE | MAX_VALUE | +--------------------------+----------------+-----------+-----------+ | event_scheduler | ON | 0 | 0 | | max_connections | 200 | 1 | 100000 | | validate_password.policy | STRONG | 0 | 0 | +--------------------------+----------------+-----------+-----------+