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 '1995-01-01'
	and o_orderdate < cast(date '1995-01-01' + 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=1185020.04..1185020.09 rows=20 width=175) (actual time=49310.954..49310.960 rows=20 loops=1)
   Buffers: shared hit=1069178 read=356030 dirtied=223 written=356
   ->  Sort  (cost=1185020.04..1186406.53 rows=554594 width=175) (actual time=49310.950..49310.953 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=1069178 read=356030 dirtied=223 written=356
         ->  HashAggregate  (cost=1164716.56..1170262.50 rows=554594 width=175) (actual time=48775.484..49143.631 rows=354848 loops=1)
               Buffers: shared hit=1069175 read=356030 dirtied=223 written=356
               ->  Hash Join  (cost=399367.56..1150851.71 rows=554594 width=175) (actual time=9034.924..44736.524 rows=941663 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1069175 read=356030 dirtied=223 written=356
                     ->  Hash Join  (cost=399366.00..1143224.48 rows=554594 width=153) (actual time=9034.885..44023.772 rows=941663 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1069174 read=356030 dirtied=223 written=356
                           ->  Merge Join  (cost=330338.00..1063104.60 rows=554594 width=12) (actual time=5116.568..37937.946 rows=941663 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1069168 read=320758 dirtied=223 written=210
                                 ->  Sort  (cost=330337.98..331751.69 rows=565484 width=8) (actual time=5116.115..5299.115 rows=562080 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50924kB
                                       Buffers: shared hit=228224 read=2327 dirtied=223 written=6
                                       ->  Bitmap Heap Scan on orders  (cost=12278.19..276308.45 rows=565484 width=8) (actual time=644.812..4799.082 rows=562080 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                             Buffers: shared hit=228224 read=2327 dirtied=223 written=6
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12136.82 rows=565484 width=0) (actual time=534.601..534.601 rows=566607 loops=1)
                                                   Index Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                                   Buffers: shared hit=2 read=1617 written=6
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..687284.47 rows=14843518 width=12) (actual time=0.225..29148.616 rows=14822843 loops=1)
                                       Buffers: shared hit=840944 read=318431 written=204
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3916.251..3916.251 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=6 read=35272 written=146
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.012..2431.933 rows=1500000 loops=1)
                                       Buffers: shared hit=6 read=35272 written=146
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.017..0.017 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=0.006..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 49363.891 ms
(40 rows)

COMMIT;
COMMIT