Re: Subquery with range uses filesort

[David Marcus]

I created InnoDB versions of the tables on my development computer.

select
PlayerID, PlayerName, PlayerPrimaryClub, PlayerCountry,
HistoryEvent, HistoryDate, HistoryFinalMean, HistoryFinalStDev
from Player
join History on
HistoryPlayer = PlayerID
and HistoryEvent =
( select HistoryEvent
from History
where HistoryPlayer = PlayerID and HistoryDate <= '2012-06-30'
order by HistoryDate desc, HistoryDirector desc limit 0,1 )
where PlayerID in (...)

InnoDB
id,select_type,table,type,possible_keys,key,key_len,ref,rows,filtered,Extra
1,PRIMARY,Player,ALL,PRIMARY,NULL,NULL,NULL,51938,19.99,"Using where"
1,PRIMARY,History,eq_ref,"PRIMARY,EventReportID,PlayerDateDirector,EventInitialMean,EventFinalMean",PRIMARY,8,"func,rc_innodb.Player.PlayerID",1,100.00,"Using where"
2,"DEPENDENT SUBQUERY",History,ref,PlayerDateDirector,PlayerDateDirector,4,rc_innodb.Player.PlayerID,3,100.00,"Using where; Using index; Using filesort"

InnoDB
Development
Duration / Fetch
17.160 sec / 15.584 sec

Seems rather slow.