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:
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.
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 27.4, “Using the Event Scheduler”
).
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”
).
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.
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_
xxx
commands
of the client/server protocol and
Com_
xxx
status
variables. See
Section 7.1.10, “Server Status Variables”
.
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.
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
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.