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=929445.73..929446.23 rows=200 width=8) (actual time=68216.328..68216.332 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=285783 read=5805 written=248
   ->  HashAggregate  (cost=929436.09..929438.09 rows=200 width=8) (actual time=68216.210..68216.220 rows=46 loops=1)
         Buffers: shared hit=285780 read=5805 written=248
         ->  HashAggregate  (cost=891936.09..906936.09 rows=1500000 width=8) (actual time=66987.433..67804.046 rows=1500000 loops=1)
               Buffers: shared hit=285780 read=5805 written=248
               ->  Hash Right Join  (cost=69028.00..816565.69 rows=15074080 width=8) (actual time=1235.362..49219.530 rows=15353498 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=285780 read=5805 written=248
                     ->  Seq Scan on orders  (cost=0.00..446056.09 rows=15074080 width=8) (actual time=0.036..12838.882 rows=14853477 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161523
                           Buffers: shared hit=250503 read=5804 written=248
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1233.291..1233.291 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=35277 read=1
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.022..682.155 rows=1500000 loops=1)
                                 Buffers: shared hit=35277 read=1
 Total runtime: 68242.936 ms
(21 rows)

COMMIT;
COMMIT