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=845348.04..845348.54 rows=200 width=8) (actual time=38965.303..38965.307 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=200103 read=88700 written=1227
   ->  HashAggregate  (cost=845338.40..845340.40 rows=200 width=8) (actual time=38965.204..38965.209 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=200100 read=88700 written=1227
         ->  HashAggregate  (cost=807838.40..822838.40 rows=1500000 width=8) (actual time=37857.511..38632.301 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=200100 read=88700 written=1227
               ->  Hash Right Join  (cost=69028.00..733438.13 rows=14880055 width=8) (actual time=1297.751..23293.270 rows=15337628 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=200100 read=88700 written=1227
                     ->  Seq Scan on orders  (cost=0.00..441209.30 rows=14880055 width=8) (actual time=0.029..9392.651 rows=14837607 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162393
                           Buffers: shared hit=193742 read=59780 written=269
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1282.236..1282.236 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=6358 read=28920 written=958
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.010..742.205 rows=1500000 loops=1)
                                 Buffers: shared hit=6358 read=28920 written=958
 Planning time: 3.115 ms
 Execution time: 38989.087 ms
(24 rows)

COMMIT;
COMMIT