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 '1994-09-01'
	and o_orderdate < cast(date '1994-09-01' + 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=1197926.98..1197927.03 rows=20 width=176) (actual time=47945.646..47945.653 rows=20 loops=1)
   Buffers: shared hit=745749 read=680000 dirtied=454 written=13195
   ->  Sort  (cost=1197926.98..1199364.16 rows=574873 width=176) (actual time=47945.642..47945.646 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=745749 read=680000 dirtied=454 written=13195
         ->  HashAggregate  (cost=1176881.08..1182629.81 rows=574873 width=176) (actual time=47470.031..47790.688 rows=378524 loops=1)
               Buffers: shared hit=745746 read=680000 dirtied=454 written=13195
               ->  Hash Join  (cost=402628.36..1162509.26 rows=574873 width=176) (actual time=10844.424..43126.519 rows=1135690 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=745746 read=680000 dirtied=454 written=13195
                     ->  Hash Join  (cost=402626.80..1154603.19 rows=574873 width=154) (actual time=10844.389..42326.878 rows=1135690 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=745745 read=680000 dirtied=454 written=13195
                           ->  Merge Join  (cost=333598.80..1074077.73 rows=574873 width=12) (actual time=8232.128..37363.124 rows=1135690 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=710467 read=680000 dirtied=454 written=13195
                                 ->  Sort  (cost=333598.78..335052.70 rows=581570 width=8) (actual time=8231.941..8450.077 rows=567772 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51191kB
                                       Buffers: shared hit=111297 read=121099 written=12710
                                       ->  Bitmap Heap Scan on orders  (cost=12631.08..277914.63 rows=581570 width=8) (actual time=680.004..7557.480 rows=567772 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                             Buffers: shared hit=111297 read=121099 written=12710
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12485.69 rows=581570 width=0) (actual time=561.420..561.420 rows=575161 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                                   Buffers: shared hit=2 read=1644 written=204
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694272.57 rows=15019923 width=12) (actual time=0.082..25252.965 rows=14808165 loops=1)
                                       Buffers: shared hit=599170 read=558901 dirtied=454 written=485
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2610.138..2610.138 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=0.014..1294.331 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  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=0.007..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 48000.677 ms
(40 rows)

COMMIT;
COMMIT