db1098:3316:

root@db1098.eqiad.wmnet[frwiki]> show create table change_tag\G
*************************** 1. row ***************************
       Table: change_tag
Create Table: CREATE TABLE `change_tag` (
  `ct_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `ct_rc_id` int(10) unsigned DEFAULT NULL,
  `ct_log_id` int(10) unsigned DEFAULT NULL,
  `ct_rev_id` int(10) unsigned DEFAULT NULL,
  `ct_params` blob DEFAULT NULL,
  `ct_tag_id` int(10) unsigned NOT NULL,
  PRIMARY KEY (`ct_id`),
  UNIQUE KEY `ct_rc_tag_id` (`ct_rc_id`,`ct_tag_id`),
  UNIQUE KEY `ct_log_tag_id` (`ct_log_id`,`ct_tag_id`),
  KEY `ct_tag_id_id` (`ct_tag_id`,`ct_rc_id`,`ct_rev_id`,`ct_log_id`)
) ENGINE=InnoDB AUTO_INCREMENT=31843215 DEFAULT CHARSET=binary ROW_FORMAT=COMPRESSED
1 row in set (0.001 sec)

root@db1098.eqiad.wmnet[frwiki]> explain SELECT /* DifferenceEngine::loadRevisionData */ ct_tag_id AS `value` FROM `change_tag` WHERE ct_rev_id = 178004903 /* 53cc390a825e0a18df7723cd34285e2d db1098:3316 frwiki 2s */
    -> ;
+------+-------------+------------+-------+---------------+--------------+---------+------+----------+--------------------------+
| id   | select_type | table      | type  | possible_keys | key          | key_len | ref  | rows     | Extra                    |
+------+-------------+------------+-------+---------------+--------------+---------+------+----------+--------------------------+
|    1 | SIMPLE      | change_tag | index | NULL          | ct_tag_id_id | 19      | NULL | 25496139 | Using where; Using index |
+------+-------------+------------+-------+---------------+--------------+---------+------+----------+--------------------------+
1 row in set (0.000 sec)







db1096:3316

root@db1096.eqiad.wmnet[frwiki]> show create table change_tag\G
*************************** 1. row ***************************
       Table: change_tag
Create Table: CREATE TABLE `change_tag` (
  `ct_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `ct_rc_id` int(10) unsigned DEFAULT NULL,
  `ct_log_id` int(10) unsigned DEFAULT NULL,
  `ct_rev_id` int(10) unsigned DEFAULT NULL,
  `ct_params` blob DEFAULT NULL,
  `ct_tag_id` int(10) unsigned NOT NULL,
  PRIMARY KEY (`ct_id`),
  UNIQUE KEY `ct_rc_tag_id` (`ct_rc_id`,`ct_tag_id`),
  UNIQUE KEY `ct_log_tag_id` (`ct_log_id`,`ct_tag_id`),
  UNIQUE KEY `ct_rev_tag_id` (`ct_rev_id`,`ct_tag_id`),
  KEY `ct_tag_id_id` (`ct_tag_id`,`ct_rc_id`,`ct_rev_id`,`ct_log_id`)
) ENGINE=InnoDB AUTO_INCREMENT=31843234 DEFAULT CHARSET=binary ROW_FORMAT=COMPRESSED
1 row in set (0.001 sec)


root@db1096.eqiad.wmnet[frwiki]> explain SELECT /* DifferenceEngine::loadRevisionData */ ct_tag_id AS `value` FROM `change_tag` WHERE ct_rev_id = 178004903 /* 53cc390a825e0a18df7723cd34285e2d db1098:3316 frwiki 2s */;
+------+-------------+------------+------+---------------+---------------+---------+-------+------+-------------+
| id   | select_type | table      | type | possible_keys | key           | key_len | ref   | rows | Extra       |
+------+-------------+------------+------+---------------+---------------+---------+-------+------+-------------+
|    1 | SIMPLE      | change_tag | ref  | ct_rev_tag_id | ct_rev_tag_id | 5       | const | 2    | Using index |
+------+-------------+------------+------+---------------+---------------+---------+-------+------+-------------+
1 row in set (0.001 sec)