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 '%pending%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=844154.48..844154.98 rows=200 width=8) (actual time=28489.930..28489.932 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=288652 read=151
   ->  HashAggregate  (cost=844144.84..844146.84 rows=200 width=8) (actual time=28489.853..28489.859 rows=45 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=288649 read=151
         ->  HashAggregate  (cost=806644.84..821644.84 rows=1500000 width=8) (actual time=27584.384..28160.354 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=288649 read=151
               ->  Hash Right Join  (cost=69028.00..732542.96 rows=14820377 width=8) (actual time=869.032..17151.806 rows=15352283 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=288649 read=151
                     ->  Seq Scan on orders  (cost=0.00..441209.30 rows=14820377 width=8) (actual time=0.016..6644.356 rows=14852263 loops=1)
                           Filter: ((o_comment)::text !~~ '%pending%requests%'::text)
                           Rows Removed by Filter: 162737
                           Buffers: shared hit=253371 read=151
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=860.176..860.176 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=35278
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.009..414.271 rows=1500000 loops=1)
                                 Buffers: shared hit=35278
 Planning time: 4.856 ms
 Execution time: 28502.990 ms
(24 rows)

COMMIT;
COMMIT