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=923050.59..923051.09 rows=200 width=8) (actual time=74064.519..74064.520 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=284997 read=5071
   ->  HashAggregate  (cost=923040.95..923042.95 rows=200 width=8) (actual time=74064.407..74064.417 rows=46 loops=1)
         Buffers: shared hit=284994 read=5071
         ->  HashAggregate  (cost=885540.95..900540.95 rows=1500000 width=8) (actual time=72724.271..73633.398 rows=1500000 loops=1)
               Buffers: shared hit=284994 read=5071
               ->  Hash Right Join  (cost=69028.00..810920.52 rows=14924086 width=8) (actual time=1692.715..51136.599 rows=15352573 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=284994 read=5071
                     ->  Seq Scan on orders  (cost=0.00..443410.80 rows=14924086 width=8) (actual time=0.035..13468.055 rows=14852554 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162446
                           Buffers: shared hit=249722 read=5065
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1690.836..1690.836 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=35272 read=6
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.016..986.569 rows=1500000 loops=1)
                                 Buffers: shared hit=35272 read=6
 Total runtime: 74100.196 ms
(21 rows)

COMMIT;
COMMIT