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=1192983.96..1192984.01 rows=20 width=176) (actual time=37841.098..37841.105 rows=20 loops=1)
   Buffers: shared hit=693360 read=732916 written=257
   ->  Sort  (cost=1192983.96..1194415.42 rows=572584 width=176) (actual time=37841.095..37841.098 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=693360 read=732916 written=257
         ->  HashAggregate  (cost=1172021.87..1177747.71 rows=572584 width=176) (actual time=37390.829..37690.791 rows=381747 loops=1)
               Buffers: shared hit=693357 read=732916 written=257
               ->  Hash Join  (cost=401349.29..1157707.27 rows=572584 width=176) (actual time=5520.575..33624.173 rows=1148653 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=693357 read=732916 written=257
                     ->  Hash Join  (cost=401347.72..1149832.68 rows=572584 width=154) (actual time=5520.528..32915.129 rows=1148653 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=693356 read=732916 written=257
                           ->  Merge Join  (cost=332319.72..1069353.00 rows=572584 width=12) (actual time=3132.008..28260.749 rows=1148653 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=658165 read=732829 written=257
                                 ->  Sort  (cost=332319.70..333768.89 rows=579674 width=8) (actual time=3131.855..3320.771 rows=574178 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51491kB
                                       Buffers: shared hit=229411 read=2208
                                       ->  Bitmap Heap Scan on orders  (cost=12587.64..276830.75 rows=579674 width=8) (actual time=488.438..2848.335 rows=574178 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-05-01'::date) AND (o_orderdate < '1993-08-01'::date))
                                             Buffers: shared hit=229411 read=2208
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12442.72 rows=579674 width=0) (actual time=369.747..369.747 rows=578718 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-05-01'::date) AND (o_orderdate < '1993-08-01'::date))
                                                   Buffers: shared read=1650
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..691034.43 rows=14949859 width=12) (actual time=0.097..21585.457 rows=14822827 loops=1)
                                       Buffers: shared hit=428754 read=730621 written=257
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2385.883..2385.883 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35191 read=87
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.016..1105.146 rows=1500000 loops=1)
                                       Buffers: shared hit=35191 read=87
                     ->  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: 2kB
                           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
 Total runtime: 37886.535 ms
(40 rows)

COMMIT;
COMMIT