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 '1993-08-01'
	and o_orderdate < cast(date '1993-08-01' + 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=1184418.00..1184418.05 rows=20 width=175) (actual time=24099.600..24099.606 rows=20 loops=1)
   Buffers: shared hit=270759 read=1137970
   ->  Sort  (cost=1184418.00..1185840.13 rows=568853 width=175) (actual time=24099.597..24099.601 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=270759 read=1137970
         ->  HashAggregate  (cost=1163592.50..1169281.03 rows=568853 width=175) (actual time=23533.406..23949.899 rows=381828 loops=1)
               Buffers: shared hit=270756 read=1137970
               ->  Hash Join  (cost=398432.41..1149371.17 rows=568853 width=175) (actual time=4469.536..21593.274 rows=1147127 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=270756 read=1137970
                     ->  Hash Join  (cost=398430.84..1141547.88 rows=568853 width=153) (actual time=4469.502..21216.675 rows=1147127 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=270755 read=1137970
                           ->  Merge Join  (cost=329402.84..1061142.82 rows=568853 width=12) (actual time=2888.330..17437.549 rows=1147127 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=270753 read=1102694
                                 ->  Sort  (cost=329402.81..330841.17 rows=575345 width=8) (actual time=2888.186..3011.583 rows=574214 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51493kB
                                       Buffers: shared hit=36106 read=193593
                                       ->  Bitmap Heap Scan on orders  (cost=12207.18..274359.36 rows=575345 width=8) (actual time=256.980..2685.344 rows=574214 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-08-01'::date) AND (o_orderdate < '1993-11-01'::date))
                                             Buffers: shared hit=36106 read=193593
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12063.35 rows=575345 width=0) (actual time=169.516..169.516 rows=574214 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-08-01'::date) AND (o_orderdate < '1993-11-01'::date))
                                                   Buffers: shared read=1572
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..686062.39 rows=14845572 width=12) (actual time=0.112..12552.043 rows=14822991 loops=1)
                                       Buffers: shared hit=234647 read=909101
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1579.471..1579.471 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.003..695.468 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.021..0.021 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.007..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 24166.949 ms
(40 rows)

COMMIT;
COMMIT