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 '1994-03-01'
	and o_orderdate < cast(date '1994-03-01' + 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=1159028.31..1159028.36 rows=20 width=175) (actual time=30911.885..30911.894 rows=20 loops=1)
   Buffers: shared hit=753756 read=672259 written=10403
   ->  Sort  (cost=1159028.31..1160463.32 rows=574005 width=175) (actual time=30911.880..30911.884 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=753756 read=672259 written=10403
         ->  HashAggregate  (cost=1138014.19..1143754.24 rows=574005 width=175) (actual time=30291.243..30745.381 rows=381151 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=753753 read=672259 written=10403
               ->  Hash Join  (cost=353726.63..1123664.07 rows=574005 width=175) (actual time=4490.802..27320.544 rows=1147676 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=753753 read=672259 written=10403
                     ->  Hash Join  (cost=353725.07..1115769.94 rows=574005 width=153) (actual time=4490.758..26848.653 rows=1147676 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=753752 read=672259 written=10403
                           ->  Hash Join  (cost=284697.07..1038131.86 rows=574005 width=12) (actual time=2583.932..23709.592 rows=1147676 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=753750 read=636983 written=10355
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..691607.05 rows=14956835 width=12) (actual time=0.080..15469.232 rows=14807792 loops=1)
                                       Buffers: shared hit=584789 read=573641 written=8945
                                 ->  Hash  (cost=277421.73..277421.73 rows=581992 width=8) (actual time=2577.382..2577.382 rows=573132 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30580kB
                                       Buffers: shared hit=168961 read=63342 written=1410
                                       ->  Bitmap Heap Scan on orders  (cost=12637.85..277421.73 rows=581992 width=8) (actual time=314.750..2371.364 rows=573132 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Heap Blocks: exact=230645
                                             Buffers: shared hit=168961 read=63342 written=1410
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12492.35 rows=581992 width=0) (actual time=229.042..229.042 rows=579410 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1658
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1894.403..1894.403 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276 written=48
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.016..951.307 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276 written=48
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.024..0.024 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.007..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 6.118 ms
 Execution time: 30941.458 ms
(42 rows)

COMMIT;
COMMIT