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=849476.51..849477.01 rows=200 width=8) (actual time=31166.348..31166.348 rows=44 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=196661 read=93661 written=1038
   ->  HashAggregate  (cost=849466.87..849468.87 rows=200 width=8) (actual time=31166.248..31166.256 rows=44 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=196658 read=93661 written=1038
         ->  HashAggregate  (cost=811966.87..826966.87 rows=1500000 width=8) (actual time=30333.074..30845.800 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=196658 read=93661 written=1038
               ->  Hash Right Join  (cost=69028.00..737195.36 rows=14954301 width=8) (actual time=1254.729..18735.840 rows=15352295 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=196658 read=93661 written=1038
                     ->  Seq Scan on orders  (cost=0.00..443852.85 rows=14954301 width=8) (actual time=0.031..7916.198 rows=14852277 loops=1)
                           Filter: ((o_comment)::text !~~ '%pending%requests%'::text)
                           Rows Removed by Filter: 162723
                           Buffers: shared hit=196655 read=58386 written=995
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1242.904..1242.904 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=3 read=35275 written=43
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.020..779.863 rows=1500000 loops=1)
                                 Buffers: shared hit=3 read=35275 written=43
 Planning time: 3.522 ms
 Execution time: 31195.990 ms
(24 rows)

COMMIT;
COMMIT