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=919807.44..919807.94 rows=200 width=8) (actual time=84552.931..84552.934 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=152283 read=136773 written=68
   ->  HashAggregate  (cost=919797.80..919799.80 rows=200 width=8) (actual time=84552.839..84552.849 rows=46 loops=1)
         Buffers: shared hit=152280 read=136773 written=68
         ->  HashAggregate  (cost=882297.80..897297.80 rows=1500000 width=8) (actual time=83321.570..84216.671 rows=1500000 loops=1)
               Buffers: shared hit=152280 read=136773 written=68
               ->  Hash Right Join  (cost=69028.00..807973.76 rows=14864808 width=8) (actual time=4597.635..60638.410 rows=15352473 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=152280 read=136773 written=68
                     ->  Seq Scan on orders  (cost=0.00..441649.60 rows=14864808 width=8) (actual time=0.047..15563.605 rows=14852454 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162546
                           Buffers: shared hit=117053 read=136722 written=68
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=4595.326..4595.326 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=35227 read=51
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.012..818.476 rows=1500000 loops=1)
                                 Buffers: shared hit=35227 read=51
 Total runtime: 84592.812 ms
(21 rows)

COMMIT;
COMMIT