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=852124.91..852125.41 rows=200 width=8) (actual time=54658.020..54658.021 rows=46 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=245408 read=45927 written=148
   ->  HashAggregate  (cost=852115.27..852117.27 rows=200 width=8) (actual time=54657.879..54657.891 rows=46 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=245405 read=45927 written=148
         ->  HashAggregate  (cost=814615.27..829615.27 rows=1500000 width=8) (actual time=53298.839..54317.930 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=245405 read=45927 written=148
               ->  Hash Right Join  (cost=69028.00..739622.40 rows=14998574 width=8) (actual time=1379.495..30628.927 rows=15353489 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=245405 read=45927 written=148
                     ->  Seq Scan on orders  (cost=0.00..445615.79 rows=14998574 width=8) (actual time=0.032..10411.176 rows=14853468 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161532
                           Buffers: shared hit=210413 read=45641 written=147
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1366.803..1366.803 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=34992 read=286 written=1
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.021..790.605 rows=1500000 loops=1)
                                 Buffers: shared hit=34992 read=286 written=1
 Planning time: 4.510 ms
 Execution time: 54695.903 ms
(24 rows)

COMMIT;
COMMIT