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 '1994-06-01'
	and o_orderdate < cast(date '1994-06-01' + 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=1194983.23..1194983.28 rows=20 width=176) (actual time=26103.407..26103.414 rows=20 loops=1)
   Buffers: shared hit=511401 read=908824 written=308
   ->  Sort  (cost=1194983.23..1196402.51 rows=567712 width=176) (actual time=26103.401..26103.402 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=511401 read=908824 written=308
         ->  HashAggregate  (cost=1174199.50..1179876.62 rows=567712 width=176) (actual time=25565.975..25945.557 rows=381721 loops=1)
               Buffers: shared hit=511398 read=908824 written=308
               ->  Hash Join  (cost=400957.38..1160006.70 rows=567712 width=176) (actual time=3868.765..23211.569 rows=1148326 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=511398 read=908824 written=308
                     ->  Hash Join  (cost=400955.82..1152199.10 rows=567712 width=154) (actual time=3868.704..22747.450 rows=1148326 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=511397 read=908824 written=308
                           ->  Merge Join  (cost=331927.82..1071816.86 rows=567712 width=12) (actual time=2284.193..19259.511 rows=1148326 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=476229 read=908714 written=308
                                 ->  Sort  (cost=331927.80..333360.87 rows=573229 width=8) (actual time=2284.096..2429.835 rows=574145 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51490kB
                                       Buffers: shared hit=207405 read=24826
                                       ->  Bitmap Heap Scan on orders  (cost=12449.59..277102.02 rows=573229 width=8) (actual time=376.751..2086.479 rows=574145 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                             Buffers: shared hit=207405 read=24826
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12306.28 rows=573229 width=0) (actual time=272.060..272.060 rows=580596 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                                   Buffers: shared read=1664
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..693798.32 rows=15018995 width=12) (actual time=0.082..14534.157 rows=14807778 loops=1)
                                       Buffers: shared hit=268824 read=883888 written=308
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1582.501..1582.501 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35168 read=110
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.019..671.440 rows=1500000 loops=1)
                                       Buffers: shared hit=35168 read=110
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.042..0.042 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=0.021..0.028 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 26145.249 ms
(40 rows)

COMMIT;
COMMIT