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=927110.98..927111.48 rows=200 width=8) (actual time=67399.743..67399.745 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=258565 read=32770 written=20
   ->  HashAggregate  (cost=927101.34..927103.34 rows=200 width=8) (actual time=67399.607..67399.619 rows=46 loops=1)
         Buffers: shared hit=258562 read=32770 written=20
         ->  HashAggregate  (cost=889601.34..904601.34 rows=1500000 width=8) (actual time=66147.319..67062.183 rows=1500000 loops=1)
               Buffers: shared hit=258562 read=32770 written=20
               ->  Hash Right Join  (cost=69028.00..814609.83 rows=14998302 width=8) (actual time=1767.778..48085.351 rows=15352340 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=258562 read=32770 written=20
                     ->  Seq Scan on orders  (cost=0.00..445615.79 rows=14998302 width=8) (actual time=0.048..11427.009 rows=14852322 loops=1)
                           Filter: ((o_comment)::text !~~ '%pending%requests%'::text)
                           Rows Removed by Filter: 162678
                           Buffers: shared hit=229184 read=26870 written=20
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1765.511..1765.511 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=29378 read=5900
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.015..1024.903 rows=1500000 loops=1)
                                 Buffers: shared hit=29378 read=5900
 Total runtime: 67437.866 ms
(21 rows)

COMMIT;
COMMIT