BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	c_count,
	count(*) as custdist
from
	(
		select
			c_custkey,
			count(o_orderkey)
		from
			customer left outer join orders on
				c_custkey = o_custkey
				and o_comment not like '%pending%requests%'
		group by
			c_custkey
	) as c_orders (c_custkey, c_count)
group by
	c_count
order by
	custdist desc,
	c_count desc;
                                                                    QUERY PLAN                                                                    
--------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=853770.33..853770.83 rows=200 width=8) (actual time=37982.793..37982.796 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=195951 read=95637 written=1239
   ->  HashAggregate  (cost=853760.69..853762.69 rows=200 width=8) (actual time=37982.679..37982.693 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=195948 read=95637 written=1239
         ->  HashAggregate  (cost=816260.69..831260.69 rows=1500000 width=8) (actual time=36730.731..37644.400 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=195948 read=95637 written=1239
               ->  Hash Right Join  (cost=69028.00..740966.54 rows=15058830 width=8) (actual time=1067.237..22872.823 rows=15352345 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=195948 read=95637 written=1239
                     ->  Seq Scan on orders  (cost=0.00..446056.09 rows=15058830 width=8) (actual time=0.029..9690.755 rows=14852327 loops=1)
                           Filter: ((o_comment)::text !~~ '%pending%requests%'::text)
                           Rows Removed by Filter: 162673
                           Buffers: shared hit=160672 read=95635 written=1239
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1058.515..1058.515 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=35276 read=2
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.021..603.571 rows=1500000 loops=1)
                                 Buffers: shared hit=35276 read=2
 Planning time: 3.784 ms
 Execution time: 38009.370 ms
(24 rows)

COMMIT;
COMMIT