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=850079.31..850079.81 rows=200 width=8) (actual time=46031.733..46031.737 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=277408 read=12914 written=475
   ->  HashAggregate  (cost=850069.67..850071.67 rows=200 width=8) (actual time=46031.630..46031.639 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=277405 read=12914 written=475
         ->  HashAggregate  (cost=812569.67..827569.67 rows=1500000 width=8) (actual time=44982.842..45707.419 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=277405 read=12914 written=475
               ->  Hash Right Join  (cost=69028.00..737647.46 rows=14984441 width=8) (actual time=997.187..26952.438 rows=15337736 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=277405 read=12914 written=475
                     ->  Seq Scan on orders  (cost=0.00..443852.85 rows=14984441 width=8) (actual time=0.027..8311.816 rows=14837717 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162283
                           Buffers: shared hit=242228 read=12813 written=475
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=985.326..985.326 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=35177 read=101
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.015..560.375 rows=1500000 loops=1)
                                 Buffers: shared hit=35177 read=101
 Planning time: 2.821 ms
 Execution time: 46068.828 ms
(24 rows)

COMMIT;
COMMIT