인덱스 생성 전 실행 계획 -> Merge Left Join (cost=8192.75..441426.93 rows=4386 width=150) (actual time=102.871..9919.006 rows=4154 loops=1) Merge Cond: ((order.user_id)::text = (user.id)::text) ... 생략 -> Materialize (cost=2798.21..425278.44 rows=4075321 width=119) (actual time=79.025..8708.221 rows=4093777 loops=1) -> Merge Left Join (cost=2798...