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 '%special%accounts%'
		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=844591.08..844591.58 rows=200 width=8) (actual time=31287.910..31287.913 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=217460 read=71596 written=980
   ->  HashAggregate  (cost=844581.44..844583.44 rows=200 width=8) (actual time=31287.794..31287.802 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=217457 read=71596 written=980
         ->  HashAggregate  (cost=807081.44..822081.44 rows=1500000 width=8) (actual time=30457.530..30953.413 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=217457 read=71596 written=980
               ->  Hash Right Join  (cost=69028.00..732980.48 rows=14820192 width=8) (actual time=1247.601..20281.503 rows=15339144 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=217457 read=71596 written=980
                     ->  Seq Scan on orders  (cost=0.00..441649.60 rows=14820192 width=8) (actual time=0.021..8977.220 rows=14839128 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%accounts%'::text)
                           Rows Removed by Filter: 160872
                           Buffers: shared hit=208543 read=45232 written=297
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1231.227..1231.227 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=8914 read=26364 written=683
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.022..761.000 rows=1500000 loops=1)
                                 Buffers: shared hit=8914 read=26364 written=683
 Planning time: 4.820 ms
 Execution time: 31320.272 ms
(24 rows)

COMMIT;
COMMIT