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=921371.32..921371.82 rows=200 width=8) (actual time=95008.120..95008.123 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=276610 read=12699 written=35
   ->  HashAggregate  (cost=921361.68..921363.68 rows=200 width=8) (actual time=95008.015..95008.030 rows=46 loops=1)
         Buffers: shared hit=276607 read=12699 written=35
         ->  HashAggregate  (cost=883861.68..898861.68 rows=1500000 width=8) (actual time=93715.064..94633.490 rows=1500000 loops=1)
               Buffers: shared hit=276607 read=12699 written=35
               ->  Hash Right Join  (cost=69028.00..809312.92 rows=14909751 width=8) (actual time=3258.308..68785.022 rows=15352498 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=276607 read=12699 written=35
                     ->  Seq Scan on orders  (cost=0.00..442089.90 rows=14909751 width=8) (actual time=0.079..21098.606 rows=14852479 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162521
                           Buffers: shared hit=241329 read=12699 written=35
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=3256.018..3256.018 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=35278
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.016..1856.369 rows=1500000 loops=1)
                                 Buffers: shared hit=35278
 Total runtime: 95054.101 ms
(21 rows)

COMMIT;
COMMIT