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=852422.69..852423.19 rows=200 width=8) (actual time=42617.164..42617.168 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=278604 read=12731 written=44
   ->  HashAggregate  (cost=852413.05..852415.05 rows=200 width=8) (actual time=42617.063..42617.069 rows=45 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=278601 read=12731 written=44
         ->  HashAggregate  (cost=814913.05..829913.05 rows=1500000 width=8) (actual time=41377.631..42296.056 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=278601 read=12731 written=44
               ->  Hash Right Join  (cost=69028.00..739845.73 rows=15013463 width=8) (actual time=986.924..24337.653 rows=15352521 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=278601 read=12731 written=44
                     ->  Seq Scan on orders  (cost=0.00..445615.79 rows=15013463 width=8) (actual time=0.026..8526.339 rows=14852502 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162498
                           Buffers: shared hit=243324 read=12730 written=44
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=973.442..973.442 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=35277 read=1
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.017..556.531 rows=1500000 loops=1)
                                 Buffers: shared hit=35277 read=1
 Planning time: 2.733 ms
 Execution time: 42658.741 ms
(24 rows)

COMMIT;
COMMIT