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=846227.14..846227.64 rows=200 width=8) (actual time=38725.551..38725.551 rows=44 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=182997 read=106312 dirtied=1 written=3137
   ->  HashAggregate  (cost=846217.50..846219.50 rows=200 width=8) (actual time=38725.417..38725.424 rows=44 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=182994 read=106312 dirtied=1 written=3137
         ->  HashAggregate  (cost=808717.50..823717.50 rows=1500000 width=8) (actual time=37826.123..38416.616 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=182994 read=106312 dirtied=1 written=3137
               ->  Hash Right Join  (cost=69028.00..734317.60 rows=14879980 width=8) (actual time=903.774..23475.889 rows=15353362 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=182994 read=106312 dirtied=1 written=3137
                     ->  Seq Scan on orders  (cost=0.00..442089.90 rows=14879980 width=8) (actual time=0.039..8628.190 rows=14853341 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161659
                           Buffers: shared hit=147716 read=106312 dirtied=1 written=3137
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=880.500..880.500 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=0.021..412.276 rows=1500000 loops=1)
                                 Buffers: shared hit=35278
 Planning time: 2.366 ms
 Execution time: 38766.632 ms
(24 rows)

COMMIT;
COMMIT