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 '%special%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=928732.51..928733.01 rows=200 width=8) (actual time=68215.080..68215.083 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=291295 read=546 written=33
   ->  HashAggregate  (cost=928722.86..928724.86 rows=200 width=8) (actual time=68214.945..68214.957 rows=45 loops=1)
         Buffers: shared hit=291292 read=546 written=33
         ->  HashAggregate  (cost=891222.86..906222.86 rows=1500000 width=8) (actual time=66951.475..67853.028 rows=1500000 loops=1)
               Buffers: shared hit=291292 read=546 written=33
               ->  Hash Right Join  (cost=69028.00..816083.17 rows=15027939 width=8) (actual time=2072.765..49217.311 rows=15352527 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=291292 read=546 written=33
                     ->  Seq Scan on orders  (cost=0.00..446496.39 rows=15027939 width=8) (actual time=0.056..12910.161 rows=14852508 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162492
                           Buffers: shared hit=256014 read=546 written=33
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=2070.630..2070.630 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=35278
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.024..1280.087 rows=1500000 loops=1)
                                 Buffers: shared hit=35278
 Total runtime: 68242.276 ms
(21 rows)

COMMIT;
COMMIT