To enable or disable the execution of scheduled events, it is
necessary to set the value of the global
event_scheduler
system variable.
This requires the SUPER
privilege.
MySQL 5.1.6 introduces a privilege governing the creation,
modification, and deletion of events, the
EVENT
privilege. This privilege can
be bestowed using GRANT
. For
example, this GRANT
statement
confers the EVENT
privilege for the
schema named myschema
on the user
jon@ghidora
:
GRANT EVENT ON myschema.* TO jon@ghidora;
(We assume that this user account already exists, and that we wish for it to remain unchanged otherwise.)
To grant this same user the EVENT
privilege on all schemas, use the following statement:
GRANT EVENT ON *.* TO jon@ghidora;
The EVENT
privilege has global or
schema-level scope. Therefore, trying to grant it on a single
table results in an error as shown:
mysql> GRANT EVENT ON myschema.mytable TO jon@ghidora;
ERROR 1144 (42000): Illegal GRANT/REVOKE command; please
consult the manual to see which privileges can be used
It is important to understand that an event is executed with the
privileges of its definer, and that it cannot perform any actions
for which its definer does not have the requisite privileges. For
example, suppose that jon@ghidora
has the
EVENT
privilege for
myschema
. Suppose also that this user has the
SELECT
privilege for
myschema
, but no other privileges for this
schema. It is possible for jon@ghidora
to
create a new event such as this one:
CREATE EVENT e_store_ts ON SCHEDULE EVERY 10 SECOND DO INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP());
The user waits for a minute or so, and then performs a
SELECT * FROM mytable;
query, expecting to see
several new rows in the table. Instead, the table is empty. Since
the user does not have the INSERT
privilege for the table in question, the event has no effect.
If you inspect the MySQL error log
(
),
you can see that the event is executing, but the action it is
attempting to perform fails, as indicated by
hostname
.errRetCode=0
:
060209 22:39:44 [Note] EVEX EXECUTING event newdb.e [EXPR:10] 060209 22:39:44 [Note] EVEX EXECUTED event newdb.e [EXPR:10]. RetCode=0 060209 22:39:54 [Note] EVEX EXECUTING event newdb.e [EXPR:10] 060209 22:39:54 [Note] EVEX EXECUTED event newdb.e [EXPR:10]. RetCode=0 060209 22:40:04 [Note] EVEX EXECUTING event newdb.e [EXPR:10] 060209 22:40:04 [Note] EVEX EXECUTED event newdb.e [EXPR:10]. RetCode=0
Since this user very likely does not have access to the error log, it is possible to verify whether the event's action statement is valid by executing it directly:
mysql> INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP());
ERROR 1142 (42000): INSERT command denied to user
'jon'@'ghidora' for table 'mytable'
Inspection of the
INFORMATION_SCHEMA.EVENTS
table shows
that e_store_ts
exists and is enabled, but its
LAST_EXECUTED
column is
NULL
:
mysql>SELECT * FROM INFORMATION_SCHEMA.EVENTS
>WHERE EVENT_NAME='e_store_ts'
>AND EVENT_SCHEMA='myschema'\G
*************************** 1. row *************************** EVENT_CATALOG: NULL EVENT_SCHEMA: myschema EVENT_NAME: e_store_ts DEFINER: jon@ghidora EVENT_BODY: SQL EVENT_DEFINITION: INSERT INTO myschema.mytable VALUES (UNIX_TIMESTAMP()) EVENT_TYPE: RECURRING EXECUTE_AT: NULL INTERVAL_VALUE: 5 INTERVAL_FIELD: SECOND SQL_MODE: NULL STARTS: 0000-00-00 00:00:00 ENDS: 0000-00-00 00:00:00 STATUS: ENABLED ON_COMPLETION: NOT PRESERVE CREATED: 2006-02-09 22:36:06 LAST_ALTERED: 2006-02-09 22:36:06 LAST_EXECUTED: NULL EVENT_COMMENT: 1 row in set (0.00 sec)
Prior to MySQL 5.1.12, there was no
EVENT_DEFINITION
column, and
EVENT_BODY
contained the SQL statement or
statements to be executed. See Section 19.20, “The INFORMATION_SCHEMA EVENTS
Table”,
for more information.
To rescind the EVENT
privilege, use
the REVOKE
statement. In this
example, the EVENT
privilege on the
schema myschema
is removed from the
jon@ghidora
user account:
REVOKE EVENT ON myschema.* FROM jon@ghidora;
Revoking the EVENT
privilege from
a user does not delete or disable any events that may have been
created by that user.
An event is not migrated or dropped as a result of renaming or dropping the user who created it.
For example, suppose that the user jon@ghidora
has been granted the EVENT
and
INSERT
privileges on the
myschema
schema. This user then creates the
following event:
CREATE EVENT e_insert ON SCHEDULE EVERY 7 SECOND DO INSERT INTO myschema.mytable;
After this event has been created, root
revokes
the EVENT
privilege for
jon@ghidora
. However,
e_insert
continues to execute, inserting a new
row into mytable
each seven seconds. The same
would be true if root
had issued either of
these statements:
DROP USER jon@ghidora;
RENAME USER jon@ghidora TO
someotherguy@ghidora;
You can verify that this is true by examining the
mysql.event
table (discussed later in this
section) or the
INFORMATION_SCHEMA.EVENTS
table (see
Section 19.20, “The INFORMATION_SCHEMA EVENTS
Table”) before and after issuing a
DROP USER
or
RENAME USER
statement.
Event definitions are stored in the mysql.event
table, which was added in MySQL 5.1.6. To drop an event created by
another user account, the MySQL root
user (or
another user with the necessary privileges) can delete rows from
this table. For example, to remove the event
e_insert
shown previously,
root
can use the following statement:
DELETE FROM mysql.event WHERE db = 'myschema' AND definer = 'jon@ghidora' AND name = 'e_insert';
It is very important to match the event name, database schema
name, and user account when deleting rows from the
mysql.event
table. This is because the same
user can create different events of the same name in different
schemas.
The namespace for scheduled events changed in MySQL 5.1.12. Prior to that MySQL version, different users could create different events having the same name in the same database; in MySQL 5.1.12 and later, that is no longer the case. When upgrading to MySQL 5.1.12 or later from MySQL 5.1.11 or earlier, it is extremely important to make sure that no events in the same database share the same name, prior to performing the upgrade.
Users' EVENT
privileges are stored
in the Event_priv
columns of the
mysql.user
and mysql.db
tables. In both cases, this column holds one of the values
'Y
' or 'N
'.
'N
' is the default.
mysql.user.Event_priv
is set to
'Y
' for a given user only if that user has the
global EVENT
privilege (that is, if
the privilege was bestowed using GRANT EVENT ON
*.*
). For a schema-level
EVENT
privilege,
GRANT
creates a row in
mysql.db
and sets that row's
Db
column to the name of the schema, the
User
column to the name of the user, and the
Event_priv
column to 'Y
'.
There should never be any need to manipulate these tables
directly, since the GRANT
EVENT
and REVOKE EVENT
statements
perform the required operations on them.
MySQL 5.1.6 introduces five status variables providing counts of event-related operations (but not of statements executed by events; see Section D.1, “Restrictions on Stored Routines, Triggers, and Events”). These are:
Com_create_event
: The number of
CREATE EVENT
statements
executed since the last server restart.
Com_alter_event
: The number of
ALTER EVENT
statements executed
since the last server restart.
Com_drop_event
: The number of
DROP EVENT
statements executed
since the last server restart.
Com_show_create_event
: The number of
SHOW CREATE EVENT
statements
executed since the last server restart.
Com_show_events
: The number of
SHOW EVENTS
statements executed
since the last server restart.
You can view current values for all of these at one time by
running the statement SHOW STATUS LIKE
'%event%';
.
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