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=930257.58..930258.08 rows=200 width=8) (actual time=66455.621..66455.624 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=228478 read=63363 written=1144
   ->  HashAggregate  (cost=930247.94..930249.94 rows=200 width=8) (actual time=66455.502..66455.511 rows=45 loops=1)
         Buffers: shared hit=228475 read=63363 written=1144
         ->  HashAggregate  (cost=892747.94..907747.94 rows=1500000 width=8) (actual time=65290.748..66113.078 rows=1500000 loops=1)
               Buffers: shared hit=228475 read=63363 written=1144
               ->  Hash Right Join  (cost=69028.00..817303.23 rows=15088942 width=8) (actual time=1788.732..47971.183 rows=15353502 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=228475 read=63363 written=1144
                     ->  Seq Scan on orders  (cost=0.00..446496.39 rows=15088942 width=8) (actual time=0.047..12129.747 rows=14853481 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161519
                           Buffers: shared hit=228472 read=28088 written=1143
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1786.648..1786.648 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=3 read=35275 written=1
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.013..1100.464 rows=1500000 loops=1)
                                 Buffers: shared hit=3 read=35275 written=1
 Total runtime: 66482.939 ms
(21 rows)

COMMIT;
COMMIT