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 '1994-11-01'
	and o_orderdate < cast(date '1994-11-01' + 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=1198089.68..1198089.73 rows=20 width=176) (actual time=40103.942..40103.951 rows=20 loops=1)
   Buffers: shared hit=632582 read=793165 dirtied=110 written=696
   ->  Sort  (cost=1198089.68..1199532.93 rows=577303 width=176) (actual time=40103.939..40103.945 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=632582 read=793165 dirtied=110 written=696
         ->  HashAggregate  (cost=1176954.82..1182727.85 rows=577303 width=176) (actual time=39519.613..39908.050 rows=382290 loops=1)
               Buffers: shared hit=632579 read=793165 dirtied=110 written=696
               ->  Hash Join  (cost=403031.87..1162522.25 rows=577303 width=176) (actual time=5372.645..35961.483 rows=1150131 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=632579 read=793165 dirtied=110 written=696
                     ->  Hash Join  (cost=403030.30..1154582.77 rows=577303 width=154) (actual time=5372.609..35246.051 rows=1150131 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=632578 read=793165 dirtied=110 written=696
                           ->  Merge Join  (cost=334002.30..1074008.71 rows=577303 width=12) (actual time=2480.919..29566.713 rows=1150131 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=597300 read=793165 dirtied=110 written=696
                                 ->  Sort  (cost=334002.28..335463.37 rows=584436 width=8) (actual time=2480.650..2688.069 rows=575597 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51558kB
                                       Buffers: shared hit=231808 read=1105
                                       ->  Bitmap Heap Scan on orders  (cost=12696.46..278023.00 rows=584436 width=8) (actual time=509.548..2252.245 rows=575597 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-11-01'::date) AND (o_orderdate < '1995-02-01'::date))
                                             Buffers: shared hit=231808 read=1105
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12550.35 rows=584436 width=0) (actual time=414.153..414.153 rows=582669 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-11-01'::date) AND (o_orderdate < '1995-02-01'::date))
                                                   Buffers: shared hit=564 read=1103
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..693787.55 rows=15009465 width=12) (actual time=0.163..23533.282 rows=14822647 loops=1)
                                       Buffers: shared hit=365492 read=792060 dirtied=110 written=696
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2889.801..2889.801 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.015..774.862 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.016..0.016 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..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 40203.204 ms
(40 rows)

COMMIT;
COMMIT