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 '1994-10-01'
	and o_orderdate < cast(date '1994-10-01' + 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=1190460.61..1190460.66 rows=20 width=175) (actual time=66665.583..66665.591 rows=20 loops=1)
   Buffers: shared hit=913433 read=512573 dirtied=347 written=6318
   ->  Sort  (cost=1190460.61..1191890.89 rows=572111 width=175) (actual time=66665.579..66665.584 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=913433 read=512573 dirtied=347 written=6318
         ->  HashAggregate  (cost=1169515.83..1175236.94 rows=572111 width=175) (actual time=66132.588..66497.283 rows=381798 loops=1)
               Buffers: shared hit=913430 read=512573 dirtied=347 written=6318
               ->  Hash Join  (cost=402112.33..1155213.05 rows=572111 width=175) (actual time=9724.172..61691.747 rows=1150166 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=913430 read=512573 dirtied=347 written=6318
                     ->  Hash Join  (cost=402110.77..1147344.97 rows=572111 width=153) (actual time=9724.134..60769.879 rows=1150166 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=913429 read=512573 dirtied=347 written=6318
                           ->  Merge Join  (cost=333082.77..1066874.75 rows=572111 width=12) (actual time=6749.405..55132.858 rows=1150166 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=884679 read=506045 dirtied=347 written=6288
                                 ->  Sort  (cost=333082.75..334541.02 rows=583309 width=8) (actual time=6749.172..7020.557 rows=574321 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51498kB
                                       Buffers: shared hit=204466 read=27818 written=1124
                                       ->  Bitmap Heap Scan on orders  (cost=12668.90..277219.54 rows=583309 width=8) (actual time=609.632..6444.234 rows=574321 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                             Buffers: shared hit=204466 read=27818 written=1124
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12523.08 rows=583309 width=0) (actual time=508.784..508.784 rows=580103 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                                   Buffers: shared read=1662
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688006.54 rows=14859122 width=12) (actual time=0.139..44314.427 rows=14808066 loops=1)
                                       Buffers: shared hit=680213 read=478227 dirtied=347 written=5164
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2972.744..2972.744 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=28750 read=6528 written=30
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.012..1624.869 rows=1500000 loops=1)
                                       Buffers: shared hit=28750 read=6528 written=30
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.018..0.018 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..0.015 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 66711.485 ms
(40 rows)

COMMIT;
COMMIT