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 '1994-04-01'
	and o_orderdate < cast(date '1994-04-01' + 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=1183525.19..1183525.24 rows=20 width=176) (actual time=22295.098..22295.107 rows=20 loops=1)
   Buffers: shared hit=290187 read=1118097
   ->  Sort  (cost=1183525.19..1184930.45 rows=562102 width=176) (actual time=22295.095..22295.102 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=290187 read=1118097
         ->  HashAggregate  (cost=1162946.84..1168567.86 rows=562102 width=176) (actual time=21670.320..22138.382 rows=379114 loops=1)
               Buffers: shared hit=290184 read=1118097
               ->  Hash Join  (cost=397347.38..1148894.29 rows=562102 width=176) (actual time=4396.167..19727.687 rows=1138282 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=290184 read=1118097
                     ->  Hash Join  (cost=397345.82..1141163.83 rows=562102 width=154) (actual time=4396.127..19362.847 rows=1138282 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=290183 read=1118097
                           ->  Merge Join  (cost=328317.82..1060893.79 rows=562102 width=12) (actual time=2967.647..16667.504 rows=1138282 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=290181 read=1082821
                                 ->  Sort  (cost=328317.80..329736.70 rows=567561 width=8) (actual time=2967.522..3113.147 rows=568743 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51236kB
                                       Buffers: shared hit=39458 read=189798
                                       ->  Bitmap Heap Scan on orders  (cost=12039.40..274074.81 rows=567561 width=8) (actual time=262.084..2748.538 rows=568743 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Buffers: shared hit=39458 read=189798
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11897.51 rows=567561 width=0) (actual time=174.605..174.605 rows=568743 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared read=1556
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..686940.76 rows=14870565 width=12) (actual time=0.087..11661.487 rows=14822950 loops=1)
                                       Buffers: shared hit=250723 read=893023
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1426.803..1426.803 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.004..687.224 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.022..0.022 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=0.008..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 22330.313 ms
(40 rows)

COMMIT;
COMMIT