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%accounts%'
		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=920570.49..920570.99 rows=200 width=8) (actual time=74564.160..74564.164 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=148201 read=140855 written=6
   ->  HashAggregate  (cost=920560.85..920562.85 rows=200 width=8) (actual time=74564.071..74564.079 rows=46 loops=1)
         Buffers: shared hit=148198 read=140855 written=6
         ->  HashAggregate  (cost=883060.85..898060.85 rows=1500000 width=8) (actual time=73401.014..74217.704 rows=1500000 loops=1)
               Buffers: shared hit=148198 read=140855 written=6
               ->  Hash Right Join  (cost=69028.00..808584.20 rows=14895330 width=8) (actual time=2240.940..52923.558 rows=15353957 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=148198 read=140855 written=6
                     ->  Seq Scan on orders  (cost=0.00..441649.60 rows=14895330 width=8) (actual time=0.039..12330.528 rows=14853941 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%accounts%'::text)
                           Rows Removed by Filter: 161059
                           Buffers: shared hit=118874 read=134901 written=6
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=2238.984..2238.984 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=29324 read=5954
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.011..808.681 rows=1500000 loops=1)
                                 Buffers: shared hit=29324 read=5954
 Total runtime: 74625.077 ms
(21 rows)

COMMIT;
COMMIT