A silly torturous PG plan

gistfile1.txt

                                                                 QUERY PLAN                                                                 
--------------------------------------------------------------------------------------------------------------------------------------------
 Append  (cost=1124.07..1134.09 rows=201 width=136) (actual time=13.030..13.052 rows=13 loops=1)
   CTE months
     ->  Function Scan on generate_series x  (cost=0.00..25.00 rows=1000 width=4) (actual time=0.042..0.064 rows=12 loops=1)
   CTE monthly_income
     ->  HashAggregate  (cost=293.73..293.74 rows=1 width=42) (actual time=12.623..12.625 rows=10 loops=1)
           ->  Seq Scan on ledger  (cost=0.00..293.52 rows=12 width=42) (actual time=10.223..12.497 rows=27 loops=1)
                 Filter: ((account ~ 'Income:Consulting'::text) AND ((jtags ->> 'Client'::text) IS NOT NULL))
                 Rows Removed by Filter: 2741
   CTE retainer_income
     ->  HashAggregate  (cost=621.10..623.10 rows=200 width=40) (actual time=0.202..0.206 rows=12 loops=1)
           ->  Nested Loop  (cost=0.00..121.10 rows=8000 width=40) (actual time=0.004..0.021 rows=96 loops=1)
                 ->  CTE Scan on months  (cost=0.00..20.00 rows=1000 width=8) (actual time=0.000..0.002 rows=12 loops=1)
                 ->  Materialize  (cost=0.00..1.12 rows=8 width=32) (actual time=0.000..0.001 rows=8 loops=12)
                       ->  Seq Scan on projects  (cost=0.00..1.08 rows=8 width=32) (actual time=0.003..0.004 rows=8 loops=1)
   CTE revenue
     ->  Merge Left Join  (cost=81.50..109.08 rows=1000 width=200) (actual time=12.964..12.973 rows=12 loops=1)
           Merge Cond: (months_1.xtn_month = retainer_income.xtn_month)
           ->  Merge Left Join  (cost=69.86..74.94 rows=1000 width=72) (actual time=12.744..12.747 rows=12 loops=1)
                 Merge Cond: (months_1.xtn_month = monthly_income.xtn_month)
                 ->  Sort  (cost=69.83..72.33 rows=1000 width=8) (actual time=0.091..0.091 rows=12 loops=1)
                       Sort Key: months_1.xtn_month
                       Sort Method: quicksort  Memory: 25kB
                       ->  CTE Scan on months months_1  (cost=0.00..20.00 rows=1000 width=8) (actual time=0.045..0.073 rows=12 loops=1)
                 ->  Materialize  (cost=0.03..0.04 rows=1 width=68) (actual time=12.647..12.649 rows=10 loops=1)
                       ->  Sort  (cost=0.03..0.04 rows=1 width=68) (actual time=12.643..12.645 rows=10 loops=1)
                             Sort Key: monthly_income.xtn_month
                             Sort Method: quicksort  Memory: 25kB
                             ->  CTE Scan on monthly_income  (cost=0.00..0.02 rows=1 width=68) (actual time=12.624..12.628 rows=10 loops=1)
           ->  Sort  (cost=11.64..12.14 rows=200 width=136) (actual time=0.216..0.217 rows=12 loops=1)
                 Sort Key: retainer_income.xtn_month
                 Sort Method: quicksort  Memory: 25kB
                 ->  CTE Scan on retainer_income  (cost=0.00..4.00 rows=200 width=136) (actual time=0.203..0.211 rows=12 loops=1)
   CTE totals
     ->  Subquery Scan on x_1  (cost=69.64..73.14 rows=200 width=104) (actual time=13.027..13.030 rows=12 loops=1)
           ->  Sort  (cost=69.64..70.14 rows=200 width=200) (actual time=13.024..13.025 rows=12 loops=1)
                 Sort Key: revenue.xtn_month
                 Sort Method: quicksort  Memory: 25kB
                 ->  HashAggregate  (cost=57.50..62.00 rows=200 width=200) (actual time=13.002..13.010 rows=12 loops=1)
                       ->  CTE Scan on revenue  (cost=0.00..20.00 rows=1000 width=200) (actual time=12.965..12.978 rows=12 loops=1)
   ->  CTE Scan on totals  (cost=0.00..4.00 rows=200 width=136) (actual time=13.029..13.038 rows=12 loops=1)
   ->  Aggregate  (cost=6.00..6.01 rows=1 width=128) (actual time=0.013..0.013 rows=1 loops=1)
         ->  CTE Scan on totals totals_1  (cost=0.00..4.00 rows=200 width=128) (actual time=0.001..0.002 rows=12 loops=1)
 Total runtime: 13.520 ms
(43 rows)

Time: 26.224 ms