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=854507.77..854508.27 rows=200 width=8) (actual time=29313.912..29313.914 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=185273 read=106568 written=119
   ->  HashAggregate  (cost=854498.13..854500.13 rows=200 width=8) (actual time=29313.822..29313.832 rows=45 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=185270 read=106568 written=119
         ->  HashAggregate  (cost=816998.13..831998.13 rows=1500000 width=8) (actual time=28470.214..29001.179 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=185270 read=106568 written=119
               ->  Hash Right Join  (cost=69028.00..741629.69 rows=15073687 width=8) (actual time=1219.545..18818.078 rows=15352527 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=185270 read=106568 written=119
                     ->  Seq Scan on orders  (cost=0.00..446496.39 rows=15073687 width=8) (actual time=0.031..8550.718 rows=14852508 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162492
                           Buffers: shared hit=185268 read=71292 written=40
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1208.744..1208.744 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=2 read=35276 written=79
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.009..779.213 rows=1500000 loops=1)
                                 Buffers: shared hit=2 read=35276 written=79
 Planning time: 4.702 ms
 Execution time: 29343.728 ms
(24 rows)

COMMIT;
COMMIT