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=921382.04..921382.54 rows=200 width=8) (actual time=68077.364..68077.369 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=249056 read=40253 written=40
   ->  HashAggregate  (cost=921372.40..921374.40 rows=200 width=8) (actual time=68077.231..68077.247 rows=46 loops=1)
         Buffers: shared hit=249053 read=40253 written=40
         ->  HashAggregate  (cost=883872.40..898872.40 rows=1500000 width=8) (actual time=66922.180..67721.059 rows=1500000 loops=1)
               Buffers: shared hit=249053 read=40253 written=40
               ->  Hash Right Join  (cost=69028.00..809321.50 rows=14910180 width=8) (actual time=1975.671..48640.140 rows=15353984 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=249053 read=40253 written=40
                     ->  Seq Scan on orders  (cost=0.00..442089.90 rows=14910180 width=8) (actual time=0.050..11422.851 rows=14853968 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%accounts%'::text)
                           Rows Removed by Filter: 161032
                           Buffers: shared hit=249051 read=4977 written=40
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1973.215..1973.215 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=0.014..1273.000 rows=1500000 loops=1)
                                 Buffers: shared hit=2 read=35276
 Total runtime: 68134.310 ms
(21 rows)

COMMIT;
COMMIT