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%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=928133.01..928133.51 rows=200 width=8) (actual time=66110.391..66110.393 rows=44 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=263959 read=26870 written=4552
   ->  HashAggregate  (cost=928123.36..928125.36 rows=200 width=8) (actual time=66110.285..66110.297 rows=44 loops=1)
         Buffers: shared hit=263956 read=26870 written=4552
         ->  HashAggregate  (cost=890623.36..905623.36 rows=1500000 width=8) (actual time=64986.364..65783.756 rows=1500000 loops=1)
               Buffers: shared hit=263956 read=26870 written=4552
               ->  Hash Right Join  (cost=69028.00..815251.33 rows=15074407 width=8) (actual time=1759.650..48825.826 rows=15353467 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=263956 read=26870 written=4552
                     ->  Seq Scan on orders  (cost=0.00..444735.19 rows=15074407 width=8) (actual time=0.034..11159.814 rows=14853446 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161554
                           Buffers: shared hit=252595 read=2953 written=211
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1757.105..1757.105 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=11361 read=23917 written=4341
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.014..1034.526 rows=1500000 loops=1)
                                 Buffers: shared hit=11361 read=23917 written=4341
 Total runtime: 66157.182 ms
(21 rows)

COMMIT;
COMMIT