26.3.23 The INFORMATION_SCHEMA PROCESSLIST Table

Inhoudsopgave

The MySQL process list indicates the operations currently being performed by the set of threads executing within the server. The PROCESSLIST table is one source of process information. For a comparison of this table with other sources, see Sources of Process Information.

The PROCESSLIST table has these columns:

ID
The connection identifier. This is the same value displayed in the Id column of the SHOW PROCESSLIST statement, displayed in the PROCESSLIST_ID column of the Performance Schema threads table, and returned by the CONNECTION_ID() function within the thread.
USER
The MySQL user who issued the statement. A value of system user refers to a nonclient thread spawned by the server to handle tasks internally, for example, a delayed-row handler thread or an I/O or SQL thread used on replica hosts. For system user, there is no host specified in the Host column. unauthenticated user refers to a thread that has become associated with a client connection but for which authentication of the client user has not yet occurred. event_scheduler refers to the thread that monitors scheduled events (see Section 25.4, “Using the Event Scheduler”).

Note

A USER value of system user is distinct from the SYSTEM_USER privilege. The former designates internal threads. The latter distinguishes the system user and regular user account categories (see Section 6.2.11, “Account Categories”).
HOST
The host name of the client issuing the statement (except for system user, for which there is no host). The host name for TCP/IP connections is reported in host_name:client_port format to make it easier to determine which client is doing what.
DB
The default database for the thread, or NULL if none has been selected.
COMMAND
The type of command the thread is executing on behalf of the client, or Sleep if the session is idle. For descriptions of thread commands, see Section 8.14, “Examining Server Thread (Process) Information”. The value of this column corresponds to the COM_xxx commands of the client/server protocol and Com_xxx status variables. See Section 5.1.10, “Server Status Variables”.
TIME
The time in seconds that the thread has been in its current state. For a replica SQL thread, the value is the number of seconds between the timestamp of the last replicated event and the real time of the replica host. See Section 17.2.3, “Replication Threads”.
STATE
An action, event, or state that indicates what the thread is doing. For descriptions of STATE values, see Section 8.14, “Examining Server Thread (Process) Information”.
Most states correspond to very quick operations. If a thread stays in a given state for many seconds, there might be a problem that needs to be investigated.
INFO
The statement the thread is executing, or NULL if it is executing no statement. The statement might be the one sent to the server, or an innermost statement if the statement executes other statements. For example, if a CALL statement executes a stored procedure that is executing a SELECT statement, the INFO value shows the SELECT statement.

Notes

PROCESSLIST is a nonstandard INFORMATION_SCHEMA table.
Like the output from the SHOW PROCESSLIST statement, the PROCESSLIST table provides information about all threads, even those belonging to other users, if you have the PROCESS privilege. Otherwise (without the PROCESS privilege), nonanonymous users have access to information about their own threads but not threads for other users, and anonymous users have no access to thread information.
If an SQL statement refers to the PROCESSLIST table, MySQL populates the entire table once, when statement execution begins, so there is read consistency during the statement. There is no read consistency for a multi-statement transaction.

The following statements are equivalent:

SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST
 
SHOW FULL PROCESSLIST

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Document heeft de 26/06/2006 gemaakt, de laatste keer de 26/10/2018 gewijzigd
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Referenties

Manuel MySQL : https://dev.mysql.com/

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