Last month's mediawiki_history snapshot is known to be broken (see below), we should label it as bad by renaming the snapshot maybe.
select snapshot, event_entity, count(*) from mediawiki_history where snapshot in ('2018-03', '2018-02', '2018-04') group by snapshot, event_entity; 2018-02 page 380400218 2018-03 page 375059982 2018-04 page 387816452 2018-02 revision 3584105448 2018-03 revision 3058000386 2018-04 revision 3661962481 2018-02 user 171245822 2018-03 user 169545580 2018-04 user 174890707