@SQLReview 

EXAMPLE:

SELECT  user_id,sum(creates) creates,sum(edits) edits,sum(deletes) deletes,sum(undeletes) undeletes  FROM `rollup_wiki_namespace_user_events`  WHERE period_id = '2' AND wiki_id = '2237' AND time_id = '2013-08-04' AND user_id IN ('166','9506','60863','246292','265341','3','5588','6595','25501','60864','60868','60907','99366','122657','867021','946826','1038387','1387629','3361105')   GROUP BY user_id, time_id


EXPLAIN:
+----+-------------+-----------------------------------+------+----------------------------------+---------+---------+-------------------+------+----------------------------------------------+
| id | select_type | table                             | type | possible_keys                    | key     | key_len | ref               | rows | Extra                                        |
+----+-------------+-----------------------------------+------+----------------------------------+---------+---------+-------------------+------+----------------------------------------------+
|  1 | SIMPLE      | rollup_wiki_namespace_user_events | ref  | PRIMARY,time_id,user_period_time | PRIMARY | 14      | const,const,const |  210 | Using where; Using temporary; Using filesort |
+----+-------------+-----------------------------------+------+----------------------------------+---------+---------+-------------------+------+----------------------------------------------+