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=1151034.09..1151034.14 rows=20 width=176) (actual time=28151.934..28151.942 rows=20 loops=1)
   Buffers: shared hit=820987 read=598567 dirtied=94 written=10280
   ->  Sort  (cost=1151034.09..1152397.54 rows=545383 width=176) (actual time=28151.930..28151.934 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=820987 read=598567 dirtied=94 written=10280
         ->  HashAggregate  (cost=1131067.81..1136521.64 rows=545383 width=176) (actual time=27588.954..28002.561 rows=371946 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=820984 read=598567 dirtied=94 written=10280
               ->  Hash Join  (cost=351545.87..1117433.24 rows=545383 width=176) (actual time=4649.912..25151.246 rows=1109498 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=820984 read=598567 dirtied=94 written=10280
                     ->  Hash Join  (cost=351544.31..1109932.66 rows=545383 width=154) (actual time=4649.870..24752.821 rows=1109498 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=820983 read=598567 dirtied=94 written=10280
                           ->  Hash Join  (cost=282516.31..1032723.91 rows=545383 width=12) (actual time=2871.759..21706.764 rows=1109498 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=820981 read=563291 dirtied=94 written=10280
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..688901.31 rows=14894107 width=12) (actual time=0.081..13402.186 rows=14808205 loops=1)
                                       Buffers: shared hit=664690 read=490330 dirtied=1 written=10268
                                 ->  Hash  (cost=275595.20..275595.20 rows=553654 width=8) (actual time=2864.466..2864.466 rows=554297 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 29845kB
                                       Buffers: shared hit=156291 read=72961 dirtied=93 written=12
                                       ->  Bitmap Heap Scan on orders  (cost=11995.39..275595.20 rows=553654 width=8) (actual time=290.115..2583.627 rows=554297 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                             Heap Blocks: exact=227664
                                             Buffers: shared hit=156291 read=72961 dirtied=93 written=12
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11856.98 rows=553654 width=0) (actual time=208.048..208.048 rows=558713 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                                   Buffers: shared read=1588
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1765.710..1765.710 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.012..897.145 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  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: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.006..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.640 ms
 Execution time: 28184.549 ms
(42 rows)

COMMIT;
COMMIT