MariaDB [skynet]> EXPLAIN EXTENDED SELECT `db`.`version`, `db`.`nodeID` FROM `version_history` AS `v` INNER JOIN `db_history` AS `db` ON `db`.`nodeID` = `v`.`linkid` WHERE `latch` = 'breadth_first' AND `origid` = '1' ORDER BY `weight` DESC LIMIT 1; SHOW WARNINGS;
+------+-------------+-------+-------+---------------+--------+---------+-----------------+------+----------+-----------------------------+
| id   | select_type | table | type  | possible_keys | key    | key_len | ref             | rows | filtered | Extra                       |
+------+-------------+-------+-------+---------------+--------+---------+-----------------+------+----------+-----------------------------+
|    1 | SIMPLE      | v     | range | latch,latch_2 | latch  | 44      | NULL            |   10 |    30.00 | Using where; Using filesort |
|    1 | SIMPLE      | db    | ref   | nodeID        | nodeID | 8       | skynet.v.linkid |    1 |   100.00 |                             |
+------+-------------+-------+-------+---------------+--------+---------+-----------------+------+----------+-----------------------------+
2 rows in set, 1 warning (0.00 sec)

+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Level | Code | Message                                                                                                                                                                                                                                                                                                                              |
+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Note  | 1003 | select `skynet`.`db`.`version` AS `version`,`skynet`.`db`.`nodeID` AS `nodeID` from `skynet`.`version_history` `v` join `skynet`.`db_history` `db` where ((`skynet`.`v`.`latch` = 'breadth_first') and (`skynet`.`v`.`origid` = 1) and (`skynet`.`db`.`nodeID` = `skynet`.`v`.`linkid`)) order by `skynet`.`v`.`weight` desc limit 1 |
+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)