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=844752.14..844752.64 rows=200 width=8) (actual time=39474.306..39474.309 rows=44 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=217689 read=71114 written=236
   ->  HashAggregate  (cost=844742.50..844744.50 rows=200 width=8) (actual time=39474.213..39474.222 rows=44 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=217686 read=71114 written=236
         ->  HashAggregate  (cost=807242.50..822242.50 rows=1500000 width=8) (actual time=38612.980..39136.833 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=217686 read=71114 written=236
               ->  Hash Right Join  (cost=69028.00..732991.20 rows=14850260 width=8) (actual time=1407.055..25720.837 rows=15338525 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=217686 read=71114 written=236
                     ->  Seq Scan on orders  (cost=0.00..441209.30 rows=14850260 width=8) (actual time=0.036..9668.853 rows=14838502 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161498
                           Buffers: shared hit=182536 read=70986 written=236
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1398.111..1398.111 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=35150 read=128
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.023..784.888 rows=1500000 loops=1)
                                 Buffers: shared hit=35150 read=128
 Planning time: 2.478 ms
 Execution time: 39496.696 ms
(24 rows)

COMMIT;
COMMIT