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CHANGE DRAINER
An overview of the usage of CHANGE DRAINER for the TiDB database.
/docs/dev/sql-statements/sql-statement-change-drainer/

CHANGE DRAINER

The CHANGE DRAINER statement modifies the status information for Drainer in the cluster.

Tip:

Drainer's state is automatically reported to PD while running. Only when Drainer is under abnormal circumstances and its state is inconsistent with the state information stored in PD, you can use the CHANGE DRAINER statement to modify the state information stored in PD.

Examples

{{< copyable "sql" >}}

SHOW DRAINER STATUS;
+----------|----------------|--------|--------------------|---------------------|
|  NodeID  |     Address    | State  |   Max_Commit_Ts    |    Update_Time      |
+----------|----------------|--------|--------------------|---------------------|
| drainer1 | 127.0.0.3:8249 | Online | 408553768673342532 | 2019-04-30 00:00:03 |
+----------|----------------|--------|--------------------|---------------------|
| drainer2 | 127.0.0.4:8249 | Online | 408553768673345531 | 2019-05-01 00:00:04 |
+----------|----------------|--------|--------------------|---------------------|
2 rows in set (0.00 sec)

It can be seen that drainer1's state has not been updated for more than a day, the Drainer is in an abnormal state, but the State remains Online. After using CHANGE DRAINER, the Drainer's State is changed to 'paused':

{{< copyable "sql" >}}

CHANGE DRAINER TO NODE_STATE ='paused' FOR NODE_ID 'drainer1';
Query OK, 0 rows affected (0.01 sec)

{{< copyable "sql" >}}

SHOW DRAINER STATUS;
+----------|----------------|--------|--------------------|---------------------|
|  NodeID  |     Address    | State  |   Max_Commit_Ts    |    Update_Time      |
+----------|----------------|--------|--------------------|---------------------|
| drainer1 | 127.0.0.3:8249 | Paused | 408553768673342532 | 2019-04-30 00:00:03 |
+----------|----------------|--------|--------------------|---------------------|
| drainer2 | 127.0.0.4:8249 | Online | 408553768673345531 | 2019-05-01 00:00:04 |
+----------|----------------|--------|--------------------|---------------------|
2 rows in set (0.00 sec)

MySQL compatibility

This statement is a TiDB extension to MySQL syntax.

See also