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=853164.37..853164.87 rows=200 width=8) (actual time=46720.706..46720.710 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=230399 read=61189 written=1459
   ->  HashAggregate  (cost=853154.73..853156.73 rows=200 width=8) (actual time=46720.602..46720.608 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=230396 read=61189 written=1459
         ->  HashAggregate  (cost=815654.73..830654.73 rows=1500000 width=8) (actual time=45669.687..46402.852 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=230396 read=61189 written=1459
               ->  Hash Right Join  (cost=69028.00..740512.07 rows=15028532 width=8) (actual time=971.821..27416.149 rows=15352345 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=230396 read=61189 written=1459
                     ->  Seq Scan on orders  (cost=0.00..446056.09 rows=15028532 width=8) (actual time=0.028..8413.564 rows=14852327 loops=1)
                           Filter: ((o_comment)::text !~~ '%pending%requests%'::text)
                           Rows Removed by Filter: 162673
                           Buffers: shared hit=195118 read=61189 written=1459
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=955.321..955.321 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=0.018..512.923 rows=1500000 loops=1)
                                 Buffers: shared hit=35278
 Planning time: 3.015 ms
 Execution time: 46760.497 ms
(24 rows)

COMMIT;
COMMIT