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PROCESSLIST

PROCESSLIST, just like SHOW PROCESSLIST, is used to view the requests that are being handled.

The PROCESSLIST table has additional columns not present in SHOW PROCESSLIST:

  • A DIGEST column to show the digest of the SQL statement.
  • A MEM column to show the memory used by the request that is being processed, in bytes.
  • A DISK column to show the disk usage in bytes.
  • A TxnStart column to show the start time of the transaction.
  • A RESOURCE_GROUP column to show the resource group name.
USE information_schema;
DESC processlist;

+---------------------+---------------------+------+------+---------+-------+
| Field               | Type                | Null | Key  | Default | Extra |
+---------------------+---------------------+------+------+---------+-------+
| ID                  | bigint(21) unsigned | NO   |      | 0       |       |
| USER                | varchar(16)         | NO   |      |         |       |
| HOST                | varchar(64)         | NO   |      |         |       |
| DB                  | varchar(64)         | YES  |      | NULL    |       |
| COMMAND             | varchar(16)         | NO   |      |         |       |
| TIME                | int(7)              | NO   |      | 0       |       |
| STATE               | varchar(7)          | YES  |      | NULL    |       |
| INFO                | longtext            | YES  |      | NULL    |       |
| DIGEST              | varchar(64)         | YES  |      |         |       |
| MEM                 | bigint(21) unsigned | YES  |      | NULL    |       |
| DISK                | bigint(21) unsigned | YES  |      | NULL    |       |
| TxnStart            | varchar(64)         | NO   |      |         |       |
| RESOURCE_GROUP      | varchar(32)         | NO   |      |         |       |
+---------------------+---------------------+------+------+---------+-------+
13 rows in set (0.00 sec)

SELECT * FROM processlist\G

*************************** 1. row ***************************
                 ID: 2300033189772525975
               USER: root
               HOST: 127.0.0.1:51289
                 DB: NULL
            COMMAND: Query
               TIME: 0
              STATE: autocommit
               INFO: SELECT * FROM processlist
             DIGEST: dbfaa16980ec628011029f0aaf0d160f4b040885240dfc567bf760d96d374f7e
                MEM: 0
               DISK: 0
           TxnStart:
     RESOURCE_GROUP: rg1
1 row in set (0.00 sec)

Fields in the PROCESSLIST table are described as follows:

  • ID: The ID of the user connection.
  • USER: The name of the user who is executing PROCESS.
  • HOST: The address that the user is connecting to.
  • DB: The name of the currently connected default database.
  • COMMAND: The command type that PROCESS is executing.
  • TIME: The current execution duration of PROCESS, in seconds.
  • STATE: The current connection state.
  • INFO: The requested statement that is being processed.
  • DIGEST: The digest of the SQL statement.
  • MEM: The memory used by the request that is being processed, in bytes.
  • DISK: The disk usage in bytes.
  • TxnStart: The start time of the transaction.
  • RESOURCE_GROUP: The resource group name.

CLUSTER_PROCESSLIST

CLUSTER_PROCESSLIST is the cluster system table corresponding to PROCESSLIST. It is used to query the PROCESSLIST information of all TiDB nodes in the cluster. The table schema of CLUSTER_PROCESSLIST has one more column than PROCESSLIST, the INSTANCE column, which stores the address of the TiDB node this row of data is from.

SELECT * FROM information_schema.cluster_processlist;

+-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+----------------+
| INSTANCE        | ID  | USER | HOST     | DB   | COMMAND | TIME | STATE      | INFO                                                 | MEM | TxnStart                               | RESOURCE_GROUP | 
+-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+----------------+

| 10.0.1.22:10080 | 150 | u1   | 10.0.1.1 | test | Query   | 0    | autocommit | select count(*) from usertable                       | 372 | 05-28 03:54:21.230(416976223923077223) | default        |
| 10.0.1.22:10080 | 138 | root | 10.0.1.1 | test | Query   | 0    | autocommit | SELECT * FROM information_schema.cluster_processlist | 0   | 05-28 03:54:21.230(416976223923077220) | rg1            |
| 10.0.1.22:10080 | 151 | u1   | 10.0.1.1 | test | Query   | 0    | autocommit | select count(*) from usertable                       | 372 | 05-28 03:54:21.230(416976223923077224) | rg2            |
| 10.0.1.21:10080 | 15  | u2   | 10.0.1.1 | test | Query   | 0    | autocommit | select max(field0) from usertable                    | 496 | 05-28 03:54:21.230(416976223923077222) | default        |
| 10.0.1.21:10080 | 14  | u2   | 10.0.1.1 | test | Query   | 0    | autocommit | select max(field0) from usertable                    | 496 | 05-28 03:54:21.230(416976223923077225) | default        |
+-----------------+-----+------+----------+------+---------+------+------------+------------------------------------------------------+-----+----------------------------------------+----------------+
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