QUERY PLAN                                            
--------------------------------------------------------------------------------------------------
 Nested Loop  (cost=xxx rows=1 width=19)
   CTE c1
     ->  Aggregate  (cost=xxx rows=1 width=4)
           ->  Merge Join  (cost=xxx rows=100 width=4)
                 Merge Cond: (t1_1.c1 = t2.c1)
                 ->  Index Only Scan using t1_i1 on t1 t1_1  (cost=xxx rows=1000 width=4)
                 ->  Sort  (cost=xxx rows=100 width=4)
                       Sort Key: t2.c1
                       ->  Seq Scan on t2  (cost=xxx rows=100 width=4)
   ->  CTE Scan on c1  (cost=xxx rows=1 width=4)
   ->  Index Scan using t1_i1 on t1  (cost=xxx rows=1 width=15)
         Index Cond: (c1 = c1.c1)
(12 rows)

                                            QUERY PLAN                                            
--------------------------------------------------------------------------------------------------
 Nested Loop  (cost=xxx rows=2 width=19)
   CTE c1
     ->  Aggregate  (cost=xxx rows=1 width=4)
           ->  Merge Join  (cost=xxx rows=1 width=4)
                 Merge Cond: (t1_1.c1 = t2.c1)
                 ->  Index Only Scan using t1_i1 on t1 t1_1  (cost=xxx rows=1000 width=4)
                 ->  Sort  (cost=xxx rows=100 width=4)
                       Sort Key: t2.c1
                       ->  Seq Scan on t2  (cost=xxx rows=100 width=4)
   ->  CTE Scan on c1  (cost=xxx rows=1 width=4)
   ->  Index Scan using t1_i1 on t1  (cost=xxx rows=1 width=15)
         Index Cond: (c1 = c1.c1)
(12 rows)