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=929445.28..929445.78 rows=200 width=8) (actual time=68169.182..68169.184 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=289851 read=1737 written=5
   ->  HashAggregate  (cost=929435.64..929437.64 rows=200 width=8) (actual time=68169.073..68169.087 rows=45 loops=1)
         Buffers: shared hit=289848 read=1737 written=5
         ->  HashAggregate  (cost=891935.64..906935.64 rows=1500000 width=8) (actual time=66946.961..67835.478 rows=1500000 loops=1)
               Buffers: shared hit=289848 read=1737 written=5
               ->  Hash Right Join  (cost=69028.00..816565.33 rows=15074062 width=8) (actual time=1304.637..47926.441 rows=15338672 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=289848 read=1737 written=5
                     ->  Seq Scan on orders  (cost=0.00..446056.09 rows=15074062 width=8) (actual time=0.034..11350.665 rows=14838651 loops=1)
                           Filter: ((o_comment)::text !~~ '%express%requests%'::text)
                           Rows Removed by Filter: 161349
                           Buffers: shared hit=255122 read=1185 written=5
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1302.479..1302.479 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=34726 read=552
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.014..731.009 rows=1500000 loops=1)
                                 Buffers: shared hit=34726 read=552
 Total runtime: 68226.536 ms
(21 rows)

COMMIT;
COMMIT