1. query

select * from a, b

where a.id = b.id

order by id

2. query

select * from a, b

where a.id = b.id

order by id asc limit 10

두 쿼리의 explain  Extra 결과는

1. key =>              /    Extra => Using where; Using temporary; Using filesort

2. key => PRIMARY /    Extra   => Using where

limit 이 붙고 안 붙고의 차이가 뭘까요?