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 '%pending%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=848736.58..848737.08 rows=200 width=8) (actual time=46030.691..46030.694 rows=44 loops=1)
   Sort Key: (count(*)), (count(orders.o_orderkey))
   Sort Method: quicksort  Memory: 27kB
   Buffers: shared hit=215495 read=74573 written=1192
   ->  HashAggregate  (cost=848726.94..848728.94 rows=200 width=8) (actual time=46030.573..46030.587 rows=44 loops=1)
         Group Key: count(orders.o_orderkey)
         Buffers: shared hit=215492 read=74573 written=1192
         ->  HashAggregate  (cost=811226.94..826226.94 rows=1500000 width=8) (actual time=44963.537..45701.478 rows=1500000 loops=1)
               Group Key: customer.c_custkey
               Buffers: shared hit=215492 read=74573 written=1192
               ->  Hash Right Join  (cost=69028.00..736529.91 rows=14939407 width=8) (actual time=1008.449..23612.886 rows=15352288 loops=1)
                     Hash Cond: (orders.o_custkey = customer.c_custkey)
                     Buffers: shared hit=215492 read=74573 written=1192
                     ->  Seq Scan on orders  (cost=0.00..443410.80 rows=14939407 width=8) (actual time=0.028..8229.728 rows=14852270 loops=1)
                           Filter: ((o_comment)::text !~~ '%pending%requests%'::text)
                           Rows Removed by Filter: 162730
                           Buffers: shared hit=182567 read=72220 written=1192
                     ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=4) (actual time=994.239..994.239 rows=1500000 loops=1)
                           Buckets: 2097152  Batches: 1  Memory Usage: 69119kB
                           Buffers: shared hit=32925 read=2353
                           ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=4) (actual time=0.019..546.275 rows=1500000 loops=1)
                                 Buffers: shared hit=32925 read=2353
 Planning time: 3.368 ms
 Execution time: 46064.321 ms
(24 rows)

COMMIT;
COMMIT