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=927231.68..927232.18 rows=200 width=8) (actual time=61801.792..61801.794 rows=45 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=251891 read=39950 written=5
   ->  HashAggregate  (cost=927222.04..927224.04 rows=200 width=8) (actual time=61801.690..61801.702 rows=45 loops=1)
         Buffers: shared hit=251888 read=39950 written=5
         ->  HashAggregate  (cost=889722.04..904722.04 rows=1500000 width=8) (actual time=60794.357..61477.887 rows=1500000 loops=1)
               Buffers: shared hit=251888 read=39950 written=5
               ->  Hash Right Join  (cost=69028.00..814882.51 rows=14967906 width=8) (actual time=1529.404..43267.394 rows=15337702 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=251888 read=39950 written=5
                     ->  Seq Scan on orders  (cost=0.00..446496.39 rows=14967906 width=8) (actual time=0.043..10261.242 rows=14837683 loops=1)
                           Filter: ((o_comment)::text !~~ '%special%requests%'::text)
                           Rows Removed by Filter: 162317
                           Buffers: shared hit=251886 read=4674 written=5
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=1527.241..1527.241 rows=1500000 loops=1)
                           Buckets: 262144  Batches: 1  Memory Usage: 52735kB
                           Buffers: shared hit=2 read=35276
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.013..879.951 rows=1500000 loops=1)
                                 Buffers: shared hit=2 read=35276
 Total runtime: 61842.881 ms
(21 rows)

COMMIT;
COMMIT