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 '%unusual%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=929552.58..929553.08 rows=200 width=8) (actual time=94167.135..94167.138 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=266777 read=25317 written=157
   ->  HashAggregate  (cost=929542.94..929544.94 rows=200 width=8) (actual time=94167.027..94167.033 rows=46 loops=1)
         Buffers: shared hit=266774 read=25317 written=157
         ->  HashAggregate  (cost=892042.94..907042.94 rows=1500000 width=8) (actual time=92986.196..93827.802 rows=1500000 loops=1)
               Buffers: shared hit=266774 read=25317 written=157
               ->  Hash Right Join  (cost=69028.00..816827.29 rows=15043130 width=8) (actual time=3361.451..68183.220 rows=15353656 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=266774 read=25317 written=157
                     ->  Seq Scan on orders  (cost=0.00..446936.69 rows=15043130 width=8) (actual time=0.036..18735.828 rows=14853638 loops=1)
                           Filter: ((o_comment)::text !~~ '%unusual%requests%'::text)
                           Rows Removed by Filter: 161362
                           Buffers: shared hit=249445 read=7368 written=157
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=3359.534..3359.534 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=17329 read=17949
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.014..2459.074 rows=1500000 loops=1)
                                 Buffers: shared hit=17329 read=17949
 Total runtime: 94219.599 ms
(21 rows)

COMMIT;
COMMIT