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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.
  • A SESSION_ALIAS column to show the alias of the current session.
  • A ROWS_AFFECTED column to show the number of rows currently affected by the statement.
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   |      |         |       |
| SESSION_ALIAS  | varchar(64)         | NO   |      |         |       |
| ROWS_AFFECTED  | bigint(21) unsigned | YES  |      | NULL    |       |
+----------------+---------------------+------+------+---------+-------+

SELECT * FROM information_schema.processlist\G

*************************** 1. row ***************************
            ID: 1268776964
          USER: root
          HOST: 127.0.0.1:59922
            DB: NULL
       COMMAND: Query
          TIME: 0
         STATE: autocommit
          INFO: SELECT * FROM information_schema.processlist
        DIGEST: 4b5e7cdd5d3ed84d6c1a6d56403a3d512554b534313caf296268abdec1c9ea99
           MEM: 0
          DISK: 0
      TxnStart:
RESOURCE_GROUP: default
 SESSION_ALIAS:
 ROWS_AFFECTED: 0

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.
  • SESSION_ALIAS: The alias of the current session.
  • ROWS_AFFECTED: The number of rows currently affected by the statement.

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                                                 | DIGEST                                                           | MEM  | DISK | TxnStart                               | RESOURCE_GROUP | SESSION_ALIAS | ROWS_AFFECTED |
+-----------------+------------+------+-----------------+------+---------+------+------------+------------------------------------------------------+------------------------------------------------------------------+------+------+----------------------------------------+----------------+---------------+---------------+
| 127.0.0.1:10080 | 1268776964 | root | 127.0.0.1:59922 | NULL | Query   |    0 | autocommit | SELECT * FROM information_schema.cluster_processlist | b1e38e59fbbc3e2b35546db5c8053040db989a497ac6cd71ff8dd4394395701a |    0 |    0 | 07-29 12:39:24.282(451471727468740609) | default        |               |             0 |
+-----------------+------------+------+-----------------+------+---------+------+------------+------------------------------------------------------+------------------------------------------------------------------+------+------+----------------------------------------+----------------+---------------+---------------+
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