# The `mysql.tidb` Table

+ Since 5.0:
  + The configuration rows are also available as global variables
  + Configurations can be done by both **`mysql.tidb`** table or global variables (Recommended)
  + Don't omit the key word **`GLOBAL`**

```
tidb> ~!@SHOW GLOBAL VARIABLES LIKE "tidb_gc%"@!~;
+------------------------+--------+
| Variable_name          | Value  |
+------------------------+--------+
| tidb_gc_concurrency    | -1     |
| tidb_gc_enable         | ON     |
| tidb_gc_life_time      | 10m0s  |
| tidb_gc_max_wait_time  | 86400  |
| tidb_gc_run_interval   | 10m0s  |
| tidb_gc_scan_lock_mode | LEGACY |
+------------------------+--------+
6 rows in set (0.01 sec)

tidb> SELECT @@global.tidb_gc_life_time;
+----------------------------+
| @@global.tidb_gc_life_time |
+----------------------------+
| 10m0s                      |
+----------------------------+
1 row in set (0.00 sec)

tidb> SET @@global.tidb_gc_life_time = "20m";
Query OK, 0 rows affected (0.08 sec)

```
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