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 '1994-08-01'
	and o_orderdate < cast(date '1994-08-01' + 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=1181708.03..1181708.08 rows=20 width=176) (actual time=44194.753..44194.763 rows=20 loops=1)
   Buffers: shared hit=431496 read=982851 written=20407
   ->  Sort  (cost=1181708.03..1183091.48 rows=553380 width=176) (actual time=44194.749..44194.755 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=431496 read=982851 written=20407
         ->  HashAggregate  (cost=1161448.99..1166982.79 rows=553380 width=176) (actual time=43661.692..44027.627 rows=381504 loops=1)
               Buffers: shared hit=431493 read=982851 written=20407
               ->  Hash Join  (cost=396872.13..1147614.49 rows=553380 width=176) (actual time=7020.836..39747.136 rows=1146551 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=431493 read=982851 written=20407
                     ->  Hash Join  (cost=396870.57..1140003.95 rows=553380 width=154) (actual time=7020.779..38999.897 rows=1146551 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=431492 read=982851 written=20407
                           ->  Merge Join  (cost=327842.57..1059908.35 rows=553380 width=12) (actual time=3099.072..32113.236 rows=1146551 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=431490 read=947575 written=20407
                                 ->  Sort  (cost=327842.55..329244.00 rows=560582 width=8) (actual time=3098.831..3307.474 rows=573742 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51471kB
                                       Buffers: shared hit=215246 read=15151
                                       ->  Bitmap Heap Scan on orders  (cost=11879.86..274316.59 rows=560582 width=8) (actual time=440.595..2821.604 rows=573742 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                             Buffers: shared hit=215246 read=15151
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11739.72 rows=560582 width=0) (actual time=314.955..314.955 rows=574883 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                                   Buffers: shared read=1570
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..686599.95 rows=14851661 width=12) (actual time=0.153..25407.150 rows=14823192 loops=1)
                                       Buffers: shared hit=216244 read=932424 written=20407
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=3919.722..3919.722 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=0.010..1538.030 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.032..0.032 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..0.015 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 44296.753 ms
(40 rows)

COMMIT;
COMMIT