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 '1994-01-01'
	and o_orderdate < cast(date '1994-01-01' + 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=1192121.91..1192121.96 rows=20 width=176) (actual time=37496.108..37496.116 rows=20 loops=1)
   Buffers: shared hit=500719 read=926530 dirtied=108 written=32812
   ->  Sort  (cost=1192121.91..1193518.75 rows=558738 width=176) (actual time=37496.103..37496.108 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=500719 read=926530 dirtied=108 written=32812
         ->  HashAggregate  (cost=1171666.71..1177254.09 rows=558738 width=176) (actual time=36961.430..37332.267 rows=375126 loops=1)
               Buffers: shared hit=500716 read=926530 dirtied=108 written=32812
               ->  Hash Join  (cost=400206.42..1157698.26 rows=558738 width=176) (actual time=4285.819..32989.159 rows=1121466 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=500716 read=926530 dirtied=108 written=32812
                     ->  Hash Join  (cost=400204.85..1150014.05 rows=558738 width=154) (actual time=4285.776..32302.460 rows=1121466 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=500715 read=926530 dirtied=108 written=32812
                           ->  Merge Join  (cost=331176.85..1069811.29 rows=558738 width=12) (actual time=2524.466..28295.049 rows=1121466 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=465437 read=926530 dirtied=108 written=32812
                                 ->  Sort  (cost=331176.83..332591.87 rows=566014 width=8) (actual time=2524.291..2711.443 rows=560646 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50857kB
                                       Buffers: shared hit=222827 read=8223
                                       ->  Bitmap Heap Scan on orders  (cost=12295.63..277092.84 rows=566014 width=8) (actual time=377.597..2282.276 rows=560646 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Buffers: shared hit=222827 read=8223
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12154.13 rows=566014 width=0) (actual time=294.340..294.340 rows=566864 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared hit=2 read=1623
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692755.00 rows=14984805 width=12) (actual time=0.128..22369.975 rows=14822499 loops=1)
                                       Buffers: shared hit=242610 read=918307 dirtied=108 written=32812
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1759.498..1759.498 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.012..773.819 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  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: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.007..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 37546.901 ms
(40 rows)

COMMIT;
COMMIT