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 '1994-01-01'
	and o_orderdate < cast(date '1994-01-01' + 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=1156100.08..1156100.13 rows=20 width=175) (actual time=27815.033..27815.041 rows=20 loops=1)
   Buffers: shared hit=755139 read=671402 dirtied=1158 written=953
   ->  Sort  (cost=1156100.08..1157486.32 rows=554499 width=175) (actual time=27815.029..27815.032 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=755139 read=671402 dirtied=1158 written=953
         ->  HashAggregate  (cost=1135800.07..1141345.06 rows=554499 width=175) (actual time=27415.914..27672.492 rows=375156 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=755136 read=671402 dirtied=1158 written=953
               ->  Hash Join  (cost=352756.01..1121937.59 rows=554499 width=175) (actual time=4694.907..23406.673 rows=1121539 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=755136 read=671402 dirtied=1158 written=953
                     ->  Hash Join  (cost=352754.45..1114311.67 rows=554499 width=153) (actual time=4694.859..22993.786 rows=1121539 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=755135 read=671402 dirtied=1158 written=953
                           ->  Hash Join  (cost=283726.45..1036966.18 rows=554499 width=12) (actual time=2754.227..20220.129 rows=1121539 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=744193 read=647066 dirtied=1158 written=858
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..691607.05 rows=14956835 width=12) (actual time=0.071..13803.857 rows=14822651 loops=1)
                                       Buffers: shared hit=592933 read=567508 dirtied=945 written=686
                                 ->  Hash  (cost=276698.34..276698.34 rows=562214 width=8) (actual time=2747.150..2747.150 rows=560668 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30094kB
                                       Buffers: shared hit=151260 read=79558 dirtied=213 written=172
                                       ->  Bitmap Heap Scan on orders  (cost=12211.13..276698.34 rows=562214 width=8) (actual time=309.329..2534.006 rows=560668 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Heap Blocks: exact=229197
                                             Buffers: shared hit=151260 read=79558 dirtied=213 written=172
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12070.57 rows=562214 width=0) (actual time=225.446..225.446 rows=566327 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared hit=31 read=1590 written=29
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1921.163..1921.163 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=10942 read=24336 written=95
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.019..882.959 rows=1500000 loops=1)
                                       Buffers: shared hit=10942 read=24336 written=95
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.024..0.024 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=0.006..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.114 ms
 Execution time: 27843.805 ms
(42 rows)

COMMIT;
COMMIT