Subplans :-((((

log.sql

# explain analyze select *, (select count(1) from generate_series(1,1000000) where users.id = generate_series) from users limit 1;
                                                              QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..12.57 rows=1 width=7138) (actual time=198.759..198.760 rows=1 loops=1)
   ->  Seq Scan on users  (cost=0.00..314.37 rows=25 width=7138) (actual time=198.758..198.758 rows=1 loops=1)
         SubPlan 1
           ->  Aggregate  (cost=12.51..12.52 rows=1 width=0) (actual time=198.743..198.743 rows=1 loops=1)
                 ->  Function Scan on generate_series  (cost=0.00..12.50 rows=5 width=0) (actual time=101.312..198.737 rows=1 loops=1)
                       Filter: (users.id = generate_series)
                       Rows Removed by Filter: 999999
 Planning time: 0.218 ms
 Execution time: 224.345 ms
(9 rows)

# explain analyze select *, (select count(1) from generate_series(1,1000000) where users.id = generate_series) from users limit 2;
                                                              QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..25.15 rows=2 width=7138) (actual time=196.023..299.099 rows=2 loops=1)
   ->  Seq Scan on users  (cost=0.00..314.37 rows=25 width=7138) (actual time=196.023..299.098 rows=2 loops=1)
         SubPlan 1
           ->  Aggregate  (cost=12.51..12.52 rows=1 width=0) (actual time=149.542..149.542 rows=1 loops=2)
                 ->  Function Scan on generate_series  (cost=0.00..12.50 rows=5 width=0) (actual time=50.977..149.538 rows=1 loops=2)
                       Filter: (users.id = generate_series)
                       Rows Removed by Filter: 999999
 Planning time: 0.113 ms
 Execution time: 305.532 ms
(9 rows)

# explain analyze select *, (select count(1) from generate_series(1,1000000) where users.id = generate_series) from users limit 3;
                                                              QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..37.72 rows=3 width=7138) (actual time=200.269..392.912 rows=3 loops=1)
   ->  Seq Scan on users  (cost=0.00..314.37 rows=25 width=7138) (actual time=200.269..392.911 rows=3 loops=1)
         SubPlan 1
           ->  Aggregate  (cost=12.51..12.52 rows=1 width=0) (actual time=130.964..130.964 rows=1 loops=3)
                 ->  Function Scan on generate_series  (cost=0.00..12.50 rows=5 width=0) (actual time=33.550..130.960 rows=1 loops=3)
                       Filter: (users.id = generate_series)
                       Rows Removed by Filter: 999999
 Planning time: 0.151 ms
 Execution time: 399.141 ms
(9 rows)

# explain analyze select *, (select count(1) from generate_series(1,1000000) where users.id = generate_series) from users limit 4;
                                                              QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..50.30 rows=4 width=7138) (actual time=197.629..484.626 rows=4 loops=1)
   ->  Seq Scan on users  (cost=0.00..314.37 rows=25 width=7138) (actual time=197.629..484.624 rows=4 loops=1)
         SubPlan 1
           ->  Aggregate  (cost=12.51..12.52 rows=1 width=0) (actual time=121.149..121.149 rows=1 loops=4)
                 ->  Function Scan on generate_series  (cost=0.00..12.50 rows=5 width=0) (actual time=25.212..121.145 rows=1 loops=4)
                       Filter: (users.id = generate_series)
                       Rows Removed by Filter: 999999
 Planning time: 0.178 ms
 Execution time: 491.770 ms
(9 rows)

# explain analyze select *, (select count(1) from generate_series(1,1000000) where users.id = generate_series) from users limit 5;
                                                              QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..62.87 rows=5 width=7138) (actual time=199.419..597.329 rows=5 loops=1)
   ->  Seq Scan on users  (cost=0.00..314.37 rows=25 width=7138) (actual time=199.417..597.324 rows=5 loops=1)
         SubPlan 1
           ->  Aggregate  (cost=12.51..12.52 rows=1 width=0) (actual time=119.458..119.458 rows=1 loops=5)
                 ->  Function Scan on generate_series  (cost=0.00..12.50 rows=5 width=0) (actual time=20.467..119.454 rows=1 loops=5)
                       Filter: (users.id = generate_series)
                       Rows Removed by Filter: 999999
 Planning time: 0.163 ms
 Execution time: 604.301 ms
(9 rows)

# explain analyze select *, (select count(1) from generate_series(1,1000000) where users.id = generate_series) from users limit 6;
                                                              QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..75.45 rows=6 width=7138) (actual time=202.033..706.104 rows=6 loops=1)
   ->  Seq Scan on users  (cost=0.00..314.37 rows=25 width=7138) (actual time=202.033..706.102 rows=6 loops=1)
         SubPlan 1
           ->  Aggregate  (cost=12.51..12.52 rows=1 width=0) (actual time=117.677..117.678 rows=1 loops=6)
                 ->  Function Scan on generate_series  (cost=0.00..12.50 rows=5 width=0) (actual time=16.958..117.675 rows=1 loops=6)
                       Filter: (users.id = generate_series)
                       Rows Removed by Filter: 999999
 Planning time: 0.103 ms
 Execution time: 712.495 ms
(9 rows)