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 '1993-05-01'
	and o_orderdate < cast(date '1993-05-01' + 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=1152354.38..1152354.43 rows=20 width=175) (actual time=27843.013..27843.022 rows=20 loops=1)
   Buffers: shared hit=831117 read=588352 written=480
   ->  Sort  (cost=1152354.38..1153767.67 rows=565317 width=175) (actual time=27843.009..27843.011 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=831117 read=588352 written=480
         ->  HashAggregate  (cost=1131658.33..1137311.50 rows=565317 width=175) (actual time=27467.303..27699.392 rows=381665 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=831114 read=588352 written=480
               ->  Hash Join  (cost=351431.29..1117525.40 rows=565317 width=175) (actual time=5913.746..25126.685 rows=1148567 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=831114 read=588352 written=480
                     ->  Hash Join  (cost=351429.72..1109750.73 rows=565317 width=153) (actual time=5913.703..24727.868 rows=1148567 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=831113 read=588352 written=480
                           ->  Hash Join  (cost=282401.72..1032242.98 rows=565317 width=12) (actual time=3256.202..20746.173 rows=1148567 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=831111 read=553076 written=480
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..688343.51 rows=14892004 width=12) (actual time=0.077..12654.582 rows=14823489 loops=1)
                                       Buffers: shared hit=689369 read=464181 written=364
                                 ->  Hash  (cost=275248.03..275248.03 rows=572261 width=8) (actual time=3243.804..3243.804 rows=574093 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30618kB
                                       Buffers: shared hit=141742 read=88895 written=116
                                       ->  Bitmap Heap Scan on orders  (cost=12130.11..275248.03 rows=572261 width=8) (actual time=569.607..2942.692 rows=574093 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-05-01'::date) AND (o_orderdate < '1993-08-01'::date))
                                             Heap Blocks: exact=229061
                                             Buffers: shared hit=141742 read=88895 written=116
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11987.05 rows=572261 width=0) (actual time=428.620..428.620 rows=576400 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-05-01'::date) AND (o_orderdate < '1993-08-01'::date))
                                                   Buffers: shared read=1576
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2073.367..2073.367 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=145) (actual time=0.026..944.380 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.023..0.023 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=0.007..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.311 ms
 Execution time: 27873.944 ms
(42 rows)

COMMIT;
COMMIT