VARIABLES_INFO
The VARIABLES_INFO
table provides information about the default value, current value, and scope of system variables in the current TiDB instance or TiDB cluster.
USE information_schema;
DESC variables_info;
+-----------------+---------------------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+---------------------+------+------+---------+-------+
| VARIABLE_NAME | varchar(64) | NO | | NULL | |
| VARIABLE_SCOPE | varchar(64) | NO | | NULL | |
| DEFAULT_VALUE | varchar(64) | NO | | NULL | |
| CURRENT_VALUE | varchar(64) | NO | | NULL | |
| MIN_VALUE | bigint(64) | YES | | NULL | |
| MAX_VALUE | bigint(64) unsigned | YES | | NULL | |
| POSSIBLE_VALUES | varchar(256) | YES | | NULL | |
| IS_NOOP | varchar(64) | NO | | NULL | |
+-----------------+---------------------+------+------+---------+-------+
8 rows in set (0.00 sec)
SELECT * FROM variables_info ORDER BY variable_name LIMIT 3;
+-----------------------------------+----------------+---------------+---------------+-----------+-----------+-----------------+---------+
| VARIABLE_NAME | VARIABLE_SCOPE | DEFAULT_VALUE | CURRENT_VALUE | MIN_VALUE | MAX_VALUE | POSSIBLE_VALUES | IS_NOOP |
+-----------------------------------+----------------+---------------+---------------+-----------+-----------+-----------------+---------+
| allow_auto_random_explicit_insert | SESSION,GLOBAL | OFF | OFF | NULL | NULL | NULL | NO |
| auto_increment_increment | SESSION,GLOBAL | 1 | 1 | 1 | 65535 | NULL | NO |
| auto_increment_offset | SESSION,GLOBAL | 1 | 1 | 1 | 65535 | NULL | NO |
+-----------------------------------+----------------+---------------+---------------+-----------+-----------+-----------------+---------+
3 rows in set (0.01 sec)
Fields in the VARIABLES_INFO
table are described as follows:
VARIABLE_NAME
: the name of the system variable.VARIABLE_SCOPE
: the scope of the system variable.SESSION
means that the system variable is only valid in the current session.INSTANCE
means that the system variable is valid in the TiDB instance.GLOBAL
means that the system variable is valid in the TiDB cluster.NONE
means that the system variable is read only in the TiDB cluster.DEFAULT_VALUE
: the default value of the system variable.CURRENT_VALUE
: the current value of the system variable. If the scope includesSESSION
,CURRENT_VALUE
is the value in the current session.MIN_VALUE
: the minimum value allowed for the system variable. If the system variable is not numeric,MIN_VALUE
is NULL.MAX_VALUE
: the maximum value allowed for the system variable. If the system variable is not numeric,MAX_VALUE
is NULL.POSSIBLE_VALUES
: the possible values of the system variable. If the system variable is not an enum type,POSSIBLE_VALUES
is NULL.IS_NOOP
: whether the system variable is anoop
system variable.