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 '1994-07-01'
	and o_orderdate < cast(date '1994-07-01' + 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=1186050.46..1186050.51 rows=20 width=175) (actual time=82096.138..82096.149 rows=20 loops=1)
   Buffers: shared hit=758514 read=652759 dirtied=114 written=15164
   ->  Sort  (cost=1186050.46..1187476.90 rows=570575 width=175) (actual time=82096.133..82096.141 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=758514 read=652759 dirtied=114 written=15164
         ->  HashAggregate  (cost=1165161.92..1170867.67 rows=570575 width=175) (actual time=81539.435..81929.678 rows=381218 loops=1)
               Buffers: shared hit=758511 read=652759 dirtied=114 written=15164
               ->  Hash Join  (cost=398469.79..1150897.54 rows=570575 width=175) (actual time=18627.920..77312.296 rows=1145713 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=758511 read=652759 dirtied=114 written=15164
                     ->  Hash Join  (cost=398468.23..1143050.57 rows=570575 width=153) (actual time=18627.877..76399.752 rows=1145713 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=758510 read=652759 dirtied=114 written=15164
                           ->  Merge Join  (cost=329440.23..1062611.07 rows=570575 width=12) (actual time=15987.607..71231.317 rows=1145713 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=723603 read=652388 dirtied=114 written=15164
                                 ->  Sort  (cost=329440.22..330879.32 rows=575637 width=8) (actual time=15987.338..16206.705 rows=573256 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51448kB
                                       Buffers: shared hit=7655 read=222459 written=6278
                                       ->  Bitmap Heap Scan on orders  (cost=12210.17..274366.73 rows=575637 width=8) (actual time=619.899..15625.255 rows=573256 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                             Buffers: shared hit=7655 read=222459 written=6278
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12066.27 rows=575637 width=0) (actual time=507.211..507.211 rows=573807 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                                   Buffers: shared hit=531 read=1040
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..687381.27 rows=14882937 width=12) (actual time=0.239..51359.807 rows=14808323 loops=1)
                                       Buffers: shared hit=715948 read=429929 dirtied=114 written=8886
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2638.563..2638.563 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=34907 read=371
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.012..1359.740 rows=1500000 loops=1)
                                       Buffers: shared hit=34907 read=371
                     ->  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=0.008..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 82145.709 ms
(40 rows)

COMMIT;
COMMIT