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 '1994-05-01'
	and o_orderdate < cast(date '1994-05-01' + 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=1155760.24..1155760.29 rows=20 width=176) (actual time=23015.443..23015.450 rows=20 loops=1)
   Buffers: shared hit=636429 read=786109 dirtied=248 written=347
   ->  Sort  (cost=1155760.24..1157194.66 rows=573767 width=176) (actual time=23015.440..23015.442 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=636429 read=786109 dirtied=248 written=347
         ->  HashAggregate  (cost=1134754.84..1140492.51 rows=573767 width=176) (actual time=22694.171..22888.271 rows=381752 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=636426 read=786109 dirtied=248 written=347
               ->  Hash Join  (cost=353268.80..1120410.67 rows=573767 width=176) (actual time=3645.177..20816.340 rows=1149764 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=636426 read=786109 dirtied=248 written=347
                     ->  Hash Join  (cost=353267.23..1112519.81 rows=573767 width=154) (actual time=3645.147..20436.136 rows=1149764 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=636425 read=786109 dirtied=248 written=347
                           ->  Hash Join  (cost=284239.23..1034885.30 rows=573767 width=12) (actual time=2039.250..18128.433 rows=1149764 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=626526 read=760730 dirtied=248 written=347
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..689056.88 rows=14893854 width=12) (actual time=0.102..12872.027 rows=14822845 loops=1)
                                       Buffers: shared hit=460455 read=695036 dirtied=56 written=347
                                 ->  Hash  (cost=276950.60..276950.60 rows=583056 width=8) (actual time=2033.438..2033.438 rows=574499 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30634kB
                                       Buffers: shared hit=166071 read=65694 dirtied=192
                                       ->  Bitmap Heap Scan on orders  (cost=12656.76..276950.60 rows=583056 width=8) (actual time=223.687..1853.481 rows=574499 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Heap Blocks: exact=230107
                                             Buffers: shared hit=166071 read=65694 dirtied=192
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12511.00 rows=583056 width=0) (actual time=154.568..154.568 rows=579206 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared read=1658
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1594.258..1594.258 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=9899 read=25379
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.008..718.466 rows=1500000 loops=1)
                                       Buffers: shared hit=9899 read=25379
                     ->  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: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.004..0.006 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.351 ms
 Execution time: 23040.595 ms
(42 rows)

COMMIT;
COMMIT