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=847729.60..847730.10 rows=200 width=8) (actual time=34336.261..34336.262 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=238096 read=51213
   ->  HashAggregate  (cost=847719.96..847721.96 rows=200 width=8) (actual time=34336.158..34336.167 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=238093 read=51213
         ->  HashAggregate  (cost=810219.96..825219.96 rows=1500000 width=8) (actual time=33420.195..34011.052 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=238093 read=51213
               ->  Hash Right Join  (cost=69028.00..735444.45 rows=14955103 width=8) (actual time=1138.758..20949.001 rows=15353565 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=238093 read=51213
                     ->  Seq Scan on orders  (cost=0.00..442089.90 rows=14955103 width=8) (actual time=0.027..8214.392 rows=14853547 loops=1)
                           Filter: ((o_comment)::text !~~ '%unusual%requests%'::text)
                           Rows Removed by Filter: 161453
                           Buffers: shared hit=210111 read=43917
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1125.147..1125.147 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=27982 read=7296
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.018..586.782 rows=1500000 loops=1)
                                 Buffers: shared hit=27982 read=7296
 Planning time: 3.304 ms
 Execution time: 34364.713 ms
(24 rows)

COMMIT;
COMMIT