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=930258.03..930258.53 rows=200 width=8) (actual time=68684.173..68684.176 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=246160 read=45681 written=33
   ->  HashAggregate  (cost=930248.39..930250.39 rows=200 width=8) (actual time=68684.044..68684.052 rows=45 loops=1)
         Buffers: shared hit=246157 read=45681 written=33
         ->  HashAggregate  (cost=892748.39..907748.39 rows=1500000 width=8) (actual time=67472.639..68346.175 rows=1500000 loops=1)
               Buffers: shared hit=246157 read=45681 written=33
               ->  Hash Right Join  (cost=69028.00..817303.59 rows=15088960 width=8) (actual time=2000.171..49517.260 rows=15353502 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=246157 read=45681 written=33
                     ->  Seq Scan on orders  (cost=0.00..446496.39 rows=15088960 width=8) (actual time=0.053..11974.655 rows=14853481 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161519
                           Buffers: shared hit=246155 read=10405 written=10
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1995.854..1995.854 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=2 read=35276 written=23
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.019..1269.454 rows=1500000 loops=1)
                                 Buffers: shared hit=2 read=35276 written=23
 Total runtime: 68730.161 ms
(21 rows)

COMMIT;
COMMIT