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=1142092.80..1142092.85 rows=20 width=176) (actual time=26367.674..26367.682 rows=20 loops=1)
   Buffers: shared hit=451563 read=955042
   ->  Sort  (cost=1142092.80..1143436.13 rows=537333 width=176) (actual time=26367.671..26367.677 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=451563 read=955042
         ->  HashAggregate  (cost=1122421.23..1127794.56 rows=537333 width=176) (actual time=25752.858..26204.863 rows=372215 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=451560 read=955042
               ->  Hash Join  (cost=349148.73..1108987.91 rows=537333 width=176) (actual time=4742.581..23862.506 rows=1110626 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=451560 read=955042
                     ->  Hash Join  (cost=349147.16..1101598.02 rows=537333 width=154) (actual time=4742.537..23500.216 rows=1110626 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=451559 read=955042
                           ->  Hash Join  (cost=280119.16..1024510.02 rows=537333 width=12) (actual time=2957.024..20642.647 rows=1110626 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=451557 read=919766
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..683607.70 rows=14776072 width=12) (actual time=0.070..12373.019 rows=14822992 loops=1)
                                       Buffers: shared hit=374197 read=769551
                                 ->  Hash  (cost=273293.47..273293.47 rows=546021 width=8) (actual time=2946.091..2946.091 rows=554821 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 29865kB
                                       Buffers: shared hit=77360 read=150215
                                       ->  Bitmap Heap Scan on orders  (cost=11581.15..273293.47 rows=546021 width=8) (actual time=255.090..2656.550 rows=554821 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                             Heap Blocks: exact=226058
                                             Buffers: shared hit=77360 read=150215
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11444.64 rows=546021 width=0) (actual time=167.971..167.971 rows=554821 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-02-01'::date) AND (o_orderdate < '1994-05-01'::date))
                                                   Buffers: shared read=1517
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1769.295..1769.295 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.007..748.889 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.027..0.027 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=0.010..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.049 ms
 Execution time: 26381.669 ms
(42 rows)

COMMIT;
COMMIT