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VARIABLES_INFO
Learn the `VARIABLES_INFO` information_schema table.

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 includes SESSION, 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 a noop system variable.