BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	c_custkey,
	c_name,
	sum(l_extendedprice * (1 - l_discount)) as revenue,
	c_acctbal,
	n_name,
	c_address,
	c_phone,
	c_comment
from
	customer,
	orders,
	lineitem,
	nation
where
	c_custkey = o_custkey
	and l_orderkey = o_orderkey
	and o_orderdate >= date '1994-03-01'
	and o_orderdate < cast(date '1994-03-01' + interval '3 month' as date)
	and l_returnflag = 'R'
	and c_nationkey = n_nationkey
group by
	c_custkey,
	c_name,
	c_acctbal,
	c_phone,
	n_name,
	c_address,
	c_comment
order by
	revenue desc
LIMIT 20;
                                                                                                QUERY PLAN                                                                                                 
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=1159730.76..1159730.81 rows=20 width=175) (actual time=27644.742..27644.749 rows=20 loops=1)
   Buffers: shared hit=684716 read=744017 dirtied=762 written=1598
   ->  Sort  (cost=1159730.76..1161146.18 rows=566168 width=175) (actual time=27644.738..27644.742 rows=20 loops=1)
         Sort Key: (sum((lineitem.l_extendedprice * (1::double precision - lineitem.l_discount))))
         Sort Method: top-N heapsort  Memory: 30kB
         Buffers: shared hit=684716 read=744017 dirtied=762 written=1598
         ->  HashAggregate  (cost=1139003.55..1144665.23 rows=566168 width=175) (actual time=27276.893..27502.316 rows=381409 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=684713 read=744017 dirtied=762 written=1598
               ->  Hash Join  (cost=353545.01..1124849.35 rows=566168 width=175) (actual time=5062.682..25088.553 rows=1148774 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=684713 read=744017 dirtied=762 written=1598
                     ->  Hash Join  (cost=353543.45..1117062.98 rows=566168 width=153) (actual time=5062.645..24684.941 rows=1148774 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=684712 read=744017 dirtied=762 written=1598
                           ->  Hash Join  (cost=284515.45..1039542.46 rows=566168 width=12) (actual time=3279.786..22173.479 rows=1148774 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=684691 read=708760 dirtied=762 written=1421
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..693132.30 rows=14995592 width=12) (actual time=0.085..14475.593 rows=14822519 loops=1)
                                       Buffers: shared hit=556454 read=604464 dirtied=534 written=1123
                                 ->  Hash  (cost=277350.92..277350.92 rows=573128 width=8) (actual time=3270.450..3270.450 rows=573688 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30602kB
                                       Buffers: shared hit=128237 read=104296 dirtied=228 written=298
                                       ->  Bitmap Heap Scan on orders  (cost=12447.00..277350.92 rows=573128 width=8) (actual time=409.430..3005.896 rows=573688 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Heap Blocks: exact=230873
                                             Buffers: shared hit=128237 read=104296 dirtied=228 written=298
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12303.71 rows=573128 width=0) (actual time=295.186..295.186 rows=579966 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1660 written=7
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1774.596..1774.596 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=21 read=35257 written=177
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.019..939.343 rows=1500000 loops=1)
                                       Buffers: shared hit=21 read=35257 written=177
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.022..0.022 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.008..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.336 ms
 Execution time: 27665.831 ms
(42 rows)

COMMIT;
COMMIT