It takes a very long time to load https://en.wikipedia.org/w/index.php?title=Special:RecentChanges&hidenondamaging=1 . This seems to be because the query that it executes hits an optimizer bug:
Query without hidenondamaging=1:
mysql:research@s3-analytics-slave [enwiki]> explain SELECT rc_id,rc_timestamp,rc_user,rc_user_text,rc_namespace,rc_title,rc_comment,rc_minor,rc_bot,rc_new,rc_cur_id,rc_this_oldid,rc_last_oldid,rc_type,rc_source,rc_patrolled,rc_ip,rc_old_len,rc_new_len,rc_deleted,rc_logid,rc_log_type,rc_log_action,rc_params,wl_user,wl_notificationtimestamp,page_latest,(SELECT GROUP_CONCAT(ct_tag SEPARATOR ',') FROM `change_tag` WHERE ct_rc_id=rc_id ) AS `ts_tags`,oresc_probability,'0.5' AS ores_threshold FROM `recentchanges` LEFT JOIN `watchlist` ON (wl_user = '1' AND (wl_title=rc_title) AND (wl_namespace=rc_namespace)) LEFT JOIN `page` ON ((rc_cur_id=page_id)) LEFT JOIN `ores_classification` ON ((rc_this_oldid = oresc_rev AND oresc_class = 1)) LEFT JOIN `ores_model` ON ((oresc_model = oresm_id AND oresm_is_current = 1)) WHERE rc_bot = '0' AND (rc_timestamp >= '20160912000000') AND ((oresm_name = 'damaging' OR oresm_name IS NULL)) AND ((oresm_is_current != 0 OR oresm_is_current IS NULL)) AND rc_new IN ('0','1') ORDER BY rc_timestamp DESC LIMIT 50 ;
+------+--------------------+---------------------+--------+---------------------------------------+--------------+---------+-----------------------------------------------------------------------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+--------------------+---------------------+--------+---------------------------------------+--------------+---------+-----------------------------------------------------------------------+---------+-------------+
| 1 | PRIMARY | recentchanges | ref | rc_timestamp,new_name_timestamp,tmp_2 | tmp_2 | 1 | const | 4073302 | Using where |
| 1 | PRIMARY | watchlist | eq_ref | wl_user,namespace_title | wl_user | 265 | const,enwiki.recentchanges.rc_namespace,enwiki.recentchanges.rc_title | 1 | |
| 1 | PRIMARY | page | eq_ref | PRIMARY | PRIMARY | 4 | enwiki.recentchanges.rc_cur_id | 1 | |
| 1 | PRIMARY | ores_classification | ref | oresc_winner | oresc_winner | 4 | enwiki.recentchanges.rc_this_oldid | 8 | Using where |
| 1 | PRIMARY | ores_model | eq_ref | PRIMARY | PRIMARY | 2 | enwiki.ores_classification.oresc_model | 1 | Using where |
| 2 | DEPENDENT SUBQUERY | change_tag | ref | ct_rc_id,change_tag_rc_tag | ct_rc_id | 5 | enwiki.recentchanges.rc_id | 1 | Using index |
+------+--------------------+---------------------+--------+---------------------------------------+--------------+---------+-----------------------------------------------------------------------+---------+-------------+
6 rows in set (0.00 sec)
mysql:research@s3-analytics-slave [enwiki]> SELECT rc_id,rc_timestamp,rc_user,rc_user_text,rc_namespace,rc_title,rc_comment,rc_minor,rc_bot,rc_new,rc_cur_id,rc_this_oldid,rc_last_oldid,rc_type,rc_source,rc_patrolled,rc_ip,rc_old_len,rc_new_len,rc_deleted,rc_logid,rc_log_type,rc_log_action,rc_params,wl_user,wl_notificationtimestamp,page_latest,(SELECT GROUP_CONCAT(ct_tag SEPARATOR ',') FROM `change_tag` WHERE ct_rc_id=rc_id ) AS `ts_tags`,oresc_probability,'0.5' AS ores_threshold FROM `recentchanges` LEFT JOIN `watchlist` ON (wl_user = '1' AND (wl_title=rc_title) AND (wl_namespace=rc_namespace)) LEFT JOIN `page` ON ((rc_cur_id=page_id)) LEFT JOIN `ores_classification` ON ((rc_this_oldid = oresc_rev AND oresc_class = 1)) LEFT JOIN `ores_model` ON ((oresc_model = oresm_id AND oresm_is_current = 1)) WHERE rc_bot = '0' AND (rc_timestamp >= '20160912000000') AND ((oresm_name = 'damaging' OR oresm_name IS NULL)) AND ((oresm_is_current != 0 OR oresm_is_current IS NULL)) AND rc_new IN ('0','1') ORDER BY rc_timestamp DESC LIMIT 50 ;
[...]
50 rows in set (0.00 sec)Query with hidenondamaging=1:
mysql:research@s3-analytics-slave [enwiki]> explain SELECT rc_id,rc_timestamp,rc_user,rc_user_text,rc_namespace,rc_title,rc_comment,rc_minor,rc_bot,rc_new,rc_cur_id,rc_this_oldid,rc_last_oldid,rc_type,rc_source,rc_patrolled,rc_ip,rc_old_len,rc_new_len,rc_deleted,rc_logid,rc_log_type,rc_log_action,rc_params,wl_user,wl_notificationtimestamp,page_latest,(SELECT GROUP_CONCAT(ct_tag SEPARATOR ',') FROM `change_tag` WHERE ct_rc_id=rc_id ) AS `ts_tags`,oresc_probability,'0.5' AS ores_threshold FROM `recentchanges` LEFT JOIN `watchlist` ON (wl_user = '1' AND (wl_title=rc_title) AND (wl_namespace=rc_namespace)) LEFT JOIN `page` ON ((rc_cur_id=page_id)) INNER JOIN `ores_classification` ON ((rc_this_oldid = oresc_rev AND oresc_class = 1)) LEFT JOIN `ores_model` ON ((oresc_model = oresm_id AND oresm_is_current = 1)) WHERE rc_bot = '0' AND (rc_timestamp >= '20160912000000') AND ((oresm_name = 'damaging' OR oresm_name IS NULL)) AND ((oresm_is_current != 0 OR oresm_is_current IS NULL)) AND (oresc_probability > '0.5') AND rc_patrolled = '0' AND rc_new IN ('0','1') ORDER BY rc_timestamp DESC LIMIT 50 ;
+------+--------------------+---------------------+--------+---------------------------------------------+----------+---------+-----------------------------------------------------------------------+---------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+--------------------+---------------------+--------+---------------------------------------------+----------+---------+-----------------------------------------------------------------------+---------+----------------------------------------------+
| 1 | PRIMARY | ores_classification | ALL | oresc_winner | NULL | NULL | NULL | 2903587 | Using where; Using temporary; Using filesort |
| 1 | PRIMARY | recentchanges | ref | rc_timestamp,new_name_timestamp,tmp_1,tmp_2 | tmp_1 | 4 | enwiki.ores_classification.oresc_rev | 1 | Using where |
| 1 | PRIMARY | watchlist | eq_ref | wl_user,namespace_title | wl_user | 265 | const,enwiki.recentchanges.rc_namespace,enwiki.recentchanges.rc_title | 1 | |
| 1 | PRIMARY | ores_model | eq_ref | PRIMARY | PRIMARY | 2 | enwiki.ores_classification.oresc_model | 1 | Using where |
| 1 | PRIMARY | page | eq_ref | PRIMARY | PRIMARY | 4 | enwiki.recentchanges.rc_cur_id | 1 | |
| 2 | DEPENDENT SUBQUERY | change_tag | ref | ct_rc_id,change_tag_rc_tag | ct_rc_id | 5 | enwiki.recentchanges.rc_id | 1 | Using index |
+------+--------------------+---------------------+--------+---------------------------------------------+----------+---------+-----------------------------------------------------------------------+---------+----------------------------------------------+
6 rows in set (0.04 sec)
mysql:research@s3-analytics-slave [enwiki]> SELECT rc_id,rc_timestamp,rc_user,rc_user_text,rc_namespace,rc_title,rc_comment,rc_minor,rc_bot,rc_new,rc_cur_id,rc_this_oldid,rc_last_oldid,rc_type,rc_source,rc_patrolled,rc_ip,rc_old_len,rc_new_len,rc_deleted,rc_logid,rc_log_type,rc_log_action,rc_params,wl_user,wl_notificationtimestamp,page_latest,(SELECT GROUP_CONCAT(ct_tag SEPARATOR ',') FROM `change_tag` WHERE ct_rc_id=rc_id ) AS `ts_tags`,oresc_probability,'0.5' AS ores_threshold FROM `recentchanges` LEFT JOIN `watchlist` ON (wl_user = '1' AND (wl_title=rc_title) AND (wl_namespace=rc_namespace)) LEFT JOIN `page` ON ((rc_cur_id=page_id)) INNER JOIN `ores_classification` ON ((rc_this_oldid = oresc_rev AND oresc_class = 1)) LEFT JOIN `ores_model` ON ((oresc_model = oresm_id AND oresm_is_current = 1)) WHERE rc_bot = '0' AND (rc_timestamp >= '20160912000000') AND ((oresm_name = 'damaging' OR oresm_name IS NULL)) AND ((oresm_is_current != 0 OR oresm_is_current IS NULL)) AND (oresc_probability > '0.5') AND rc_patrolled = '0' AND rc_new IN ('0','1') ORDER BY rc_timestamp DESC LIMIT 50 ;
[...]
50 rows in set (2 min 17.63 sec)