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 '1994-08-01'
	and o_orderdate < cast(date '1994-08-01' + 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=1194632.21..1194632.26 rows=20 width=176) (actual time=45497.571..45497.580 rows=20 loops=1)
   Buffers: shared hit=829301 read=598008 dirtied=1367 written=124
   ->  Sort  (cost=1194632.21..1196070.31 rows=575240 width=176) (actual time=45497.567..45497.573 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=829301 read=598008 dirtied=1367 written=124
         ->  HashAggregate  (cost=1173572.88..1179325.28 rows=575240 width=176) (actual time=44946.902..45329.936 rows=381540 loops=1)
               Buffers: shared hit=829298 read=598008 dirtied=1367 written=124
               ->  Hash Join  (cost=401978.65..1159191.88 rows=575240 width=176) (actual time=7290.327..41064.267 rows=1146655 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=829298 read=598008 dirtied=1367 written=124
                     ->  Hash Join  (cost=401977.08..1151280.77 rows=575240 width=154) (actual time=7290.280..40260.288 rows=1146655 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=829297 read=598008 dirtied=1367 written=124
                           ->  Merge Join  (cost=332949.08..1070747.97 rows=575240 width=12) (actual time=4743.750..35376.538 rows=1146655 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=794019 read=598008 dirtied=1367 written=124
                                 ->  Sort  (cost=332949.06..334404.96 rows=582360 width=8) (actual time=4743.515..4960.755 rows=573798 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51473kB
                                       Buffers: shared hit=168233 read=63854 dirtied=223
                                       ->  Bitmap Heap Scan on orders  (cost=12647.18..277183.58 rows=582360 width=8) (actual time=470.448..4278.664 rows=573798 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                             Buffers: shared hit=168233 read=63854 dirtied=223
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12501.59 rows=582360 width=0) (actual time=364.327..364.327 rows=578947 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                                   Buffers: shared read=1661
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..691722.85 rows=14964740 width=12) (actual time=0.131..26718.145 rows=14822772 loops=1)
                                       Buffers: shared hit=625786 read=534154 dirtied=1144 written=124
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2544.512..2544.512 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.013..1139.682 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.020..0.020 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=0.009..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 45552.350 ms
(40 rows)

COMMIT;
COMMIT