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=851685.71..851686.21 rows=200 width=8) (actual time=39348.598..39348.601 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=240018 read=51064 written=3531
   ->  HashAggregate  (cost=851676.07..851678.07 rows=200 width=8) (actual time=39348.498..39348.507 rows=45 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=240015 read=51064 written=3531
         ->  HashAggregate  (cost=814176.07..829176.07 rows=1500000 width=8) (actual time=38193.449..39026.670 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=240015 read=51064 written=3531
               ->  Hash Right Join  (cost=69028.00..739182.92 rows=14998629 width=8) (actual time=1365.862..23900.747 rows=15337677 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=240015 read=51064 written=3531
                     ->  Seq Scan on orders  (cost=0.00..445175.49 rows=14998629 width=8) (actual time=0.028..8527.829 rows=14837658 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162342
                           Buffers: shared hit=239590 read=16211 written=441
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1349.928..1349.928 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=425 read=34853 written=3090
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.017..805.252 rows=1500000 loops=1)
                                 Buffers: shared hit=425 read=34853 written=3090
 Planning time: 2.993 ms
 Execution time: 39382.364 ms
(24 rows)

COMMIT;
COMMIT