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 '1993-07-01'
	and o_orderdate < cast(date '1993-07-01' + 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=1187460.45..1187460.50 rows=20 width=176) (actual time=37703.909..37703.916 rows=20 loops=1)
   Buffers: shared hit=1315208 read=108937 dirtied=1115 written=20
   ->  Sort  (cost=1187460.45..1188868.17 rows=563090 width=176) (actual time=37703.905..37703.911 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=1315208 read=108937 dirtied=1115 written=20
         ->  HashAggregate  (cost=1166845.92..1172476.82 rows=563090 width=176) (actual time=37080.593..37524.818 rows=381890 loops=1)
               Buffers: shared hit=1315205 read=108937 dirtied=1115 written=20
               ->  Hash Join  (cost=399027.12..1152768.67 rows=563090 width=176) (actual time=8646.183..33481.280 rows=1148347 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1315205 read=108937 dirtied=1115 written=20
                     ->  Hash Join  (cost=399025.56..1145024.62 rows=563090 width=154) (actual time=8646.143..32748.430 rows=1148347 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1315204 read=108937 dirtied=1115 written=20
                           ->  Merge Join  (cost=329997.56..1064734.82 rows=563090 width=12) (actual time=5662.637..26934.430 rows=1148347 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1279927 read=108936 dirtied=1115 written=20
                                 ->  Sort  (cost=329997.54..331422.67 rows=570050 width=8) (actual time=5662.451..5854.090 rows=574350 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51499kB
                                       Buffers: shared hit=169020 read=61937
                                       ->  Bitmap Heap Scan on orders  (cost=12160.93..275498.68 rows=570050 width=8) (actual time=683.615..5355.030 rows=574350 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                             Buffers: shared hit=169020 read=61937
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12018.42 rows=570050 width=0) (actual time=581.891..581.891 rows=577082 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                                   Buffers: shared hit=2 read=1595
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688991.98 rows=14905662 width=12) (actual time=0.100..17683.729 rows=14823275 loops=1)
                                       Buffers: shared hit=1110907 read=46999 dirtied=1115 written=20
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2981.937..2981.937 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35277 read=1
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.014..1293.442 rows=1500000 loops=1)
                                       Buffers: shared hit=35277 read=1
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.019..0.019 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=0.008..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 37770.479 ms
(40 rows)

COMMIT;
COMMIT