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=928681.56..928682.06 rows=200 width=8) (actual time=86611.159..86611.162 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=282561 read=9027 written=2
   ->  HashAggregate  (cost=928671.91..928673.91 rows=200 width=8) (actual time=86611.061..86611.071 rows=45 loops=1)
         Buffers: shared hit=282558 read=9027 written=2
         ->  HashAggregate  (cost=891171.91..906171.91 rows=1500000 width=8) (actual time=85414.799..86254.171 rows=1500000 loops=1)
               Buffers: shared hit=282558 read=9027 written=2
               ->  Hash Right Join  (cost=69028.00..815954.35 rows=15043513 width=8) (actual time=2312.221..63652.191 rows=15352549 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=282558 read=9027 written=2
                     ->  Seq Scan on orders  (cost=0.00..446056.09 rows=15043513 width=8) (actual time=0.044..19318.510 rows=14852530 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162470
                           Buffers: shared hit=247969 read=8338
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=2310.195..2310.195 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=34589 read=689 written=2
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.013..1512.199 rows=1500000 loops=1)
                                 Buffers: shared hit=34589 read=689 written=2
 Total runtime: 86647.123 ms
(21 rows)

COMMIT;
COMMIT