Event monitor is storing events in DB when no rules defined.

mysql> select count(id) from tool_monitor_rules;

+-----------+

| count(id) |

+-----------+

|         0 |

+-----------+

1 row in set (0.18 sec)

mysql> select count(id) from tool_monitor_subscriptions;

+-----------+

| count(id) |

+-----------+

|         0 |

+-----------+

1 row in set (0.00 sec)

mysql> select count(id) from tool_monitor_events;

+-----------+

| count(id) |

+-----------+

|      3797 |

+-----------+

1 row in set (0.00 sec)

mysql> select * from tool_monitor_events limit 3;

+--------+------------------------------------+-----------+--------------+-------------------+---------------------------------------------------+----------+-------------+

| id     | eventname                          | contextid | contextlevel | contextinstanceid | link                                              | courseid | timecreated |

+--------+------------------------------------+-----------+--------------+-------------------+---------------------------------------------------+----------+-------------+

| 165540 | \mod_forum\event\discussion_viewed |       143 |           70 |                50 | https://moodle.org/mod/forum/discuss.php?d=272864 |        5 |  1414415569 |

| 165541 | \mod_forum\event\discussion_viewed |       143 |           70 |                50 | https://moodle.org/mod/forum/discuss.php?d=273627 |        5 |  1414415570 |

| 165542 | \mod_forum\event\discussion_viewed |       317 |           70 |              2429 | https://moodle.org/mod/forum/discuss.php?d=155986 |       14 |  1414415570 |

+--------+------------------------------------+-----------+--------------+-------------------+---------------------------------------------------+----------+-------------+

3 rows in set (0.10 sec)