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 '%unusual%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=851552.69..851553.19 rows=200 width=8) (actual time=28957.014..28957.017 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=214576 read=76253 written=22
   ->  HashAggregate  (cost=851543.05..851545.05 rows=200 width=8) (actual time=28956.932..28956.941 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=214573 read=76253 written=22
         ->  HashAggregate  (cost=814043.05..829043.05 rows=1500000 width=8) (actual time=27989.994..28652.794 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=214573 read=76253 written=22
               ->  Hash Right Join  (cost=69028.00..738973.08 rows=15013993 width=8) (actual time=846.948..16936.910 rows=15338732 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=214573 read=76253 written=22
                     ->  Seq Scan on orders  (cost=0.00..444735.19 rows=15013993 width=8) (actual time=0.026..7776.781 rows=14838714 loops=1)
                           Filter: ((o_comment)::text !~~ '%unusual%requests%'::text)
                           Rows Removed by Filter: 161286
                           Buffers: shared hit=179295 read=76253 written=22
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=837.445..837.445 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=0.015..463.295 rows=1500000 loops=1)
                                 Buffers: shared hit=35278
 Planning time: 2.455 ms
 Execution time: 28978.665 ms
(24 rows)

COMMIT;
COMMIT