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=1193733.54..1193733.59 rows=20 width=176) (actual time=28617.503..28617.510 rows=20 loops=1)
   Buffers: shared hit=354518 read=1063408 dirtied=116 written=56
   ->  Sort  (cost=1193733.54..1195140.38 rows=562733 width=176) (actual time=28617.499..28617.502 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=354518 read=1063408 dirtied=116 written=56
         ->  HashAggregate  (cost=1173132.09..1178759.42 rows=562733 width=176) (actual time=28108.330..28466.009 rows=371940 loops=1)
               Buffers: shared hit=354515 read=1063408 dirtied=116 written=56
               ->  Hash Join  (cost=400257.42..1159063.77 rows=562733 width=176) (actual time=4947.282..24650.803 rows=1109482 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=354515 read=1063408 dirtied=116 written=56
                     ->  Hash Join  (cost=400255.85..1151324.63 rows=562733 width=154) (actual time=4947.241..24215.103 rows=1109482 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=354514 read=1063408 dirtied=116 written=56
                           ->  Merge Join  (cost=331227.85..1071041.97 rows=562733 width=12) (actual time=2328.183..19201.288 rows=1109482 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=354511 read=1028133 dirtied=116 written=56
                                 ->  Sort  (cost=331227.83..332648.34 rows=568201 width=8) (actual time=2328.024..2459.674 rows=554225 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50556kB
                                       Buffers: shared hit=220696 read=9237
                                       ->  Bitmap Heap Scan on orders  (cost=12342.05..276919.06 rows=568201 width=8) (actual time=406.267..2125.852 rows=554225 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                             Buffers: shared hit=220696 read=9237
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12200.00 rows=568201 width=0) (actual time=317.434..317.434 rows=560363 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                                   Buffers: shared read=1603
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..693798.32 rows=15018995 width=12) (actual time=0.113..14558.487 rows=14807772 loops=1)
                                       Buffers: shared hit=133815 read=1018896 dirtied=116 written=56
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2617.394..2617.394 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=3 read=35275
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.010..920.693 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275
                     ->  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=0.005..0.007 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 28706.256 ms
(40 rows)

COMMIT;
COMMIT