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=929543.28..929543.78 rows=200 width=8) (actual time=91800.829..91800.833 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=157375 read=134719 written=31
   ->  HashAggregate  (cost=929533.64..929535.64 rows=200 width=8) (actual time=91800.712..91800.725 rows=46 loops=1)
         Buffers: shared hit=157372 read=134719 written=31
         ->  HashAggregate  (cost=892033.64..907033.64 rows=1500000 width=8) (actual time=90464.641..91443.989 rows=1500000 loops=1)
               Buffers: shared hit=157372 read=134719 written=31
               ->  Hash Right Join  (cost=69028.00..816819.85 rows=15042758 width=8) (actual time=3336.328..65255.890 rows=15352545 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=157372 read=134719 written=31
                     ->  Seq Scan on orders  (cost=0.00..446936.69 rows=15042758 width=8) (actual time=0.047..20867.148 rows=14852526 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162474
                           Buffers: shared hit=157370 read=99443 written=31
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=3334.353..3334.353 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=2 read=35276
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.015..2397.877 rows=1500000 loops=1)
                                 Buffers: shared hit=2 read=35276
 Total runtime: 91841.762 ms
(21 rows)

COMMIT;
COMMIT