Nested Loop  (cost=xxx rows=1 width=31)
   ->  Nested Loop  (cost=xxx rows=1 width=16)
         Join Filter: (ft_1.id = ft_2.id)
         ->  Foreign Scan on ft1 ft_1  (cost=xxx rows=1 width=8)
               Foreign File: /home/suzukitks/pg_hint_directory/pg_hint_plan/data/data.csv
               Foreign File Size: 42
         ->  Foreign Scan on ft1 ft_2  (cost=xxx rows=1 width=8)
               Foreign File: /home/suzukitks/pg_hint_directory/pg_hint_plan/data/data.csv
               Foreign File Size: 42
   ->  Index Scan using t1_i1 on t1  (cost=xxx rows=1 width=15)
         Index Cond: (c1 = ft_1.id)