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 '%unusual%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=849334.08..849334.58 rows=200 width=8) (actual time=38190.104..38190.105 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=201177 read=88891 written=1624
   ->  HashAggregate  (cost=849324.44..849326.44 rows=200 width=8) (actual time=38189.989..38190.003 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=201174 read=88891 written=1624
         ->  HashAggregate  (cost=811824.44..826824.44 rows=1500000 width=8) (actual time=37119.821..37885.766 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=201174 read=88891 written=1624
               ->  Hash Right Join  (cost=69028.00..736978.03 rows=14969282 width=8) (actual time=1265.642..24120.857 rows=15353558 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=201174 read=88891 written=1624
                     ->  Seq Scan on orders  (cost=0.00..443410.80 rows=14969282 width=8) (actual time=0.033..7675.377 rows=14853540 loops=1)
                           Filter: ((o_comment)::text !~~ '%unusual%requests%'::text)
                           Rows Removed by Filter: 161460
                           Buffers: shared hit=201172 read=53615 written=1615
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1246.510..1246.510 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=2 read=35276 written=9
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.013..715.646 rows=1500000 loops=1)
                                 Buffers: shared hit=2 read=35276 written=9
 Planning time: 2.754 ms
 Execution time: 38225.299 ms
(24 rows)

COMMIT;
COMMIT