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 '1993-02-01'
	and o_orderdate < cast(date '1993-02-01' + 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=1177589.45..1177589.50 rows=20 width=175) (actual time=40650.093..40650.100 rows=20 loops=1)
   Buffers: shared hit=650727 read=757915 written=39776
   ->  Sort  (cost=1177589.45..1178933.85 rows=537761 width=175) (actual time=40650.089..40650.090 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=650727 read=757915 written=39776
         ->  HashAggregate  (cost=1157902.21..1163279.82 rows=537761 width=175) (actual time=40072.421..40463.326 rows=372744 loops=1)
               Buffers: shared hit=650724 read=757915 written=39776
               ->  Hash Join  (cost=394309.78..1144458.19 rows=537761 width=175) (actual time=5293.279..31530.723 rows=1113032 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=650724 read=757915 written=39776
                     ->  Hash Join  (cost=394308.22..1137062.41 rows=537761 width=153) (actual time=5293.241..30920.672 rows=1113032 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=650723 read=757915 written=39776
                           ->  Merge Join  (cost=325280.22..1057279.19 rows=537761 width=12) (actual time=2683.907..25580.663 rows=1113032 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=622760 read=750600 written=39776
                                 ->  Sort  (cost=325280.19..326639.92 rows=543894 width=8) (actual time=2683.736..2857.719 rows=555222 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50603kB
                                       Buffers: shared hit=226720 read=1521
                                       ->  Bitmap Heap Scan on orders  (cost=11532.81..273466.22 rows=543894 width=8) (actual time=294.496..2018.185 rows=555222 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-02-01'::date) AND (o_orderdate < '1993-05-01'::date))
                                             Buffers: shared hit=226720 read=1521
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11396.84 rows=543894 width=0) (actual time=219.366..219.366 rows=556265 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-02-01'::date) AND (o_orderdate < '1993-05-01'::date))
                                                   Buffers: shared read=1521
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..686752.28 rows=14860480 width=12) (actual time=0.104..19849.093 rows=14808171 loops=1)
                                       Buffers: shared hit=396040 read=749079 written=39776
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2607.670..2607.670 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=27963 read=7315
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.012..935.645 rows=1500000 loops=1)
                                       Buffers: shared hit=27963 read=7315
                     ->  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..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 40759.650 ms
(40 rows)

COMMIT;
COMMIT