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=852112.55..852113.05 rows=200 width=8) (actual time=30556.397..30556.399 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=223561 read=67774 written=548
   ->  HashAggregate  (cost=852102.91..852104.91 rows=200 width=8) (actual time=30556.290..30556.300 rows=45 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=223558 read=67774 written=548
         ->  HashAggregate  (cost=814602.91..829602.91 rows=1500000 width=8) (actual time=29438.484..30244.680 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=223558 read=67774 written=548
               ->  Hash Right Join  (cost=69028.00..739613.13 rows=14997956 width=8) (actual time=1168.051..19352.526 rows=15354058 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=223558 read=67774 written=548
                     ->  Seq Scan on orders  (cost=0.00..445615.79 rows=14997956 width=8) (actual time=0.029..8553.700 rows=14854042 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%accounts%'::text)
                           Rows Removed by Filter: 160958
                           Buffers: shared hit=223556 read=32498 written=52
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1152.877..1152.877 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=2 read=35276 written=496
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.017..728.689 rows=1500000 loops=1)
                                 Buffers: shared hit=2 read=35276 written=496
 Planning time: 3.250 ms
 Execution time: 30585.445 ms
(24 rows)

COMMIT;
COMMIT