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 '%express%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=927008.43..927008.93 rows=200 width=8) (actual time=66040.890..66040.893 rows=44 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=289643 read=1186 dirtied=253 written=49
   ->  HashAggregate  (cost=926998.79..927000.79 rows=200 width=8) (actual time=66040.781..66040.790 rows=44 loops=1)
         Buffers: shared hit=289640 read=1186 dirtied=253 written=49
         ->  HashAggregate  (cost=889498.79..904498.79 rows=1500000 width=8) (actual time=64914.255..65705.507 rows=1500000 loops=1)
               Buffers: shared hit=289640 read=1186 dirtied=253 written=49
               ->  Hash Right Join  (cost=69028.00..814351.67 rows=15029424 width=8) (actual time=1658.609..47409.853 rows=15353467 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=289640 read=1186 dirtied=253 written=49
                     ->  Seq Scan on orders  (cost=0.00..444735.19 rows=15029424 width=8) (actual time=0.032..12074.720 rows=14853446 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161554
                           Buffers: shared hit=255079 read=469 dirtied=253 written=2
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1656.470..1656.470 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=34561 read=717 written=47
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.013..913.799 rows=1500000 loops=1)
                                 Buffers: shared hit=34561 read=717 written=47
 Total runtime: 66068.678 ms
(21 rows)

COMMIT;
COMMIT