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 '1994-02-01'
	and o_orderdate < cast(date '1994-02-01' + 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=1179349.88..1179349.93 rows=20 width=176) (actual time=40435.312..40435.316 rows=20 loops=1)
   Buffers: shared hit=1148243 read=259514 dirtied=114 written=2143
   ->  Sort  (cost=1179349.88..1180726.04 rows=550464 width=176) (actual time=40435.307..40435.309 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=1148243 read=259514 dirtied=114 written=2143
         ->  HashAggregate  (cost=1159197.60..1164702.24 rows=550464 width=176) (actual time=39874.356..40271.826 rows=371904 loops=1)
               Buffers: shared hit=1148240 read=259514 dirtied=114 written=2143
               ->  Hash Join  (cost=395918.31..1145436.00 rows=550464 width=176) (actual time=11439.848..33381.757 rows=1109371 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1148240 read=259514 dirtied=114 written=2143
                     ->  Hash Join  (cost=395916.75..1137865.55 rows=550464 width=154) (actual time=11439.804..32731.635 rows=1109371 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1148239 read=259514 dirtied=114 written=2143
                           ->  Merge Join  (cost=326888.75..1057828.27 rows=550464 width=12) (actual time=7447.324..25940.332 rows=1109371 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1113008 read=259467 dirtied=114 written=2143
                                 ->  Sort  (cost=326888.73..328281.90 rows=557269 width=8) (actual time=7447.183..7625.450 rows=554213 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50555kB
                                       Buffers: shared hit=21879 read=205697
                                       ->  Bitmap Heap Scan on orders  (cost=11821.90..273702.94 rows=557269 width=8) (actual time=422.358..7134.711 rows=554213 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                             Buffers: shared hit=21879 read=205697
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11682.59 rows=557269 width=0) (actual time=287.730..287.730 rows=554821 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                                   Buffers: shared hit=2 read=1516
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..685569.47 rows=14831634 width=12) (actual time=0.096..15135.224 rows=14808303 loops=1)
                                       Buffers: shared hit=1091129 read=53770 dirtied=114 written=2143
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=3990.210..3990.210 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35231 read=47
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.016..1011.247 rows=1500000 loops=1)
                                       Buffers: shared hit=35231 read=47
                     ->  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=0.010..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 40561.403 ms
(40 rows)

COMMIT;
COMMIT