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 '1993-10-01'
	and o_orderdate < cast(date '1993-10-01' + 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=1193343.70..1193343.75 rows=20 width=176) (actual time=37738.016..37738.023 rows=20 loops=1)
   Buffers: shared hit=820849 read=606106 dirtied=94 written=39797
   ->  Sort  (cost=1193343.70..1194775.01 rows=572522 width=176) (actual time=37738.011..37738.015 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=820849 read=606106 dirtied=94 written=39797
         ->  HashAggregate  (cost=1172383.88..1178109.10 rows=572522 width=176) (actual time=37213.356..37551.212 rows=381191 loops=1)
               Buffers: shared hit=820846 read=606106 dirtied=94 written=39797
               ->  Hash Join  (cost=401294.27..1158070.83 rows=572522 width=176) (actual time=6339.519..33702.494 rows=1147350 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=820846 read=606106 dirtied=94 written=39797
                     ->  Hash Join  (cost=401292.71..1150197.09 rows=572522 width=154) (actual time=6339.469..33008.668 rows=1147350 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=820845 read=606106 dirtied=94 written=39797
                           ->  Merge Join  (cost=332264.71..1069718.65 rows=572522 width=12) (actual time=4021.279..28406.130 rows=1147350 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=785570 read=606103 dirtied=94 written=39797
                                 ->  Sort  (cost=332264.69..333712.88 rows=579276 width=8) (actual time=4021.099..4203.751 rows=573311 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51450kB
                                       Buffers: shared hit=229833 read=1900 written=5
                                       ->  Bitmap Heap Scan on orders  (cost=12579.56..276816.70 rows=579276 width=8) (actual time=643.908..3705.145 rows=573311 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                             Buffers: shared hit=229833 read=1900 written=5
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12434.74 rows=579276 width=0) (actual time=451.369..451.369 rows=578377 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                                   Buffers: shared read=1655
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..691436.05 rows=14958523 width=12) (actual time=0.154..20913.722 rows=14807964 loops=1)
                                       Buffers: shared hit=555737 read=604203 dirtied=94 written=39792
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2316.038..2316.038 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35275 read=3
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.043..1120.439 rows=1500000 loops=1)
                                       Buffers: shared hit=35275 read=3
                     ->  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..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 37788.361 ms
(40 rows)

COMMIT;
COMMIT