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%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=846527.62..846528.12 rows=200 width=8) (actual time=52062.183..52062.186 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=212022 read=77287 dirtied=161 written=1920
   ->  HashAggregate  (cost=846517.98..846519.98 rows=200 width=8) (actual time=52062.085..52062.096 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=212019 read=77287 dirtied=161 written=1920
         ->  HashAggregate  (cost=809017.98..824017.98 rows=1500000 width=8) (actual time=50833.782..51741.610 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=212019 read=77287 dirtied=161 written=1920
               ->  Hash Right Join  (cost=69028.00..734542.96 rows=14895004 width=8) (actual time=1178.231..28326.062 rows=15337679 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=212019 read=77287 dirtied=161 written=1920
                     ->  Seq Scan on orders  (cost=0.00..442089.90 rows=14895004 width=8) (actual time=0.025..8827.083 rows=14837660 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162340
                           Buffers: shared hit=208715 read=45313 dirtied=161 written=440
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1168.671..1168.671 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=3304 read=31974 written=1480
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.013..743.012 rows=1500000 loops=1)
                                 Buffers: shared hit=3304 read=31974 written=1480
 Planning time: 3.201 ms
 Execution time: 52094.704 ms
(24 rows)

COMMIT;
COMMIT