MySQL 9.3 Reference Manual Including MySQL NDB Cluster 9.3
INFORMATION_SCHEMA.PROCESSLIST is
deprecated and subject to removal in a future MySQL release. As
such, the implementation of SHOW
PROCESSLIST which uses this table is also deprecated.
It is recommended to use the Performance Schema implementation
of PROCESSLIST instead.
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 27.5, “Using the Event Scheduler”).
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 8.2.11, “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
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 10.14, “Examining Server Thread (Process) Information”. The value of this column
corresponds to the
COM_ commands
of the client/server protocol and
xxxCom_ status
variables. See Section 7.1.10, “Server Status Variables”.
xxx
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 19.2.3, “Replication Threads”.
STATE
An action, event, or state that indicates what the thread is
doing. For descriptions of STATE values,
see Section 10.14, “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.
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
You can obtain information about use of this table by checking the
values of the server status variables
Deprecated_use_i_s_processlist_count
and
Deprecated_use_i_s_processlist_last_timestamp.
Deprecated_use_i_s_processlist_count shows the
number of times the PROCESSLIST table has been
accessed since the last server restart;
Deprecated_use_i_s_processlist_last_timestamp
provides the last time the table was accessed, as a Unix
timestamp.