Add a missing DaemonLogEvent key for garbage collection
ClosedPublic
Actions

Authored by epriestley on Oct 26 2017, 8:08 PM.

Details

Reviewers

amckinley

Commits

rPfbfed82efdde: Add a missing DaemonLogEvent key for garbage collection

Summary

See PHI176. This is issued periodically by the garbage collector. Normally this table is relatively small-ish so this missing key isn't hugely noticeable.

Test Plan

Ran ./bin/garbage collect --collector daemon.processes --trace to get the query the GC runs.

Ran DELETE FROM `daemon_logevent` WHERE epoch < 1508443504 LIMIT 100 before and after the key, saw a much better query plan afterward:

Before:

mysql> explain DELETE FROM `daemon_logevent` WHERE epoch < 1508443504 LIMIT 100;
+----+-------------+-----------------+------+---------------+------+---------+------+-------+-------------+
| id | select_type | table           | type | possible_keys | key  | key_len | ref  | rows  | Extra       |
+----+-------------+-----------------+------+---------------+------+---------+------+-------+-------------+
|  1 | SIMPLE      | daemon_logevent | ALL  | NULL          | NULL | NULL    | NULL | 19325 | Using where |
+----+-------------+-----------------+------+---------------+------+---------+------+-------+-------------+
1 row in set (0.00 sec)

After:

mysql> explain DELETE FROM `daemon_logevent` WHERE epoch < 1508443504 LIMIT 100;
+----+-------------+-----------------+-------+---------------+-----------+---------+-------+------+-------------+
| id | select_type | table           | type  | possible_keys | key       | key_len | ref   | rows | Extra       |
+----+-------------+-----------------+-------+---------------+-----------+---------+-------+------+-------------+
|  1 | SIMPLE      | daemon_logevent | range | key_epoch     | key_epoch | 4       | const |    1 | Using where |
+----+-------------+-----------------+-------+---------------+-----------+---------+-------+------+-------------+
1 row in set (0.00 sec)