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 '%express%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=849747.55..849748.05 rows=200 width=8) (actual time=30338.421..30338.424 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=163469 read=127360 dirtied=253 written=188
   ->  HashAggregate  (cost=849737.91..849739.91 rows=200 width=8) (actual time=30338.317..30338.324 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=163466 read=127360 dirtied=253 written=188
         ->  HashAggregate  (cost=812237.91..827237.91 rows=1500000 width=8) (actual time=29355.558..30034.831 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=163466 read=127360 dirtied=253 written=188
               ->  Hash Right Join  (cost=69028.00..737619.23 rows=14923736 width=8) (actual time=884.006..18037.095 rows=15338952 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=163466 read=127360 dirtied=253 written=188
                     ->  Seq Scan on orders  (cost=0.00..444735.19 rows=14923736 width=8) (actual time=0.024..8572.704 rows=14838934 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%accounts%'::text)
                           Rows Removed by Filter: 161066
                           Buffers: shared hit=128233 read=127315 dirtied=253 written=188
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=875.932..875.932 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=35233 read=45
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.016..477.760 rows=1500000 loops=1)
                                 Buffers: shared hit=35233 read=45
 Planning time: 2.824 ms
 Execution time: 30355.292 ms
(24 rows)

COMMIT;
COMMIT