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 '1994-03-01'
	and o_orderdate < cast(date '1994-03-01' + 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=1181443.70..1181443.75 rows=20 width=176) (actual time=25469.262..25469.269 rows=20 loops=1)
   Buffers: shared hit=270940 read=1137996
   ->  Sort  (cost=1181443.70..1182843.78 rows=560033 width=176) (actual time=25469.180..25469.184 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=270940 read=1137996
         ->  HashAggregate  (cost=1160941.09..1166541.42 rows=560033 width=176) (actual time=25132.911..25341.254 rows=381459 loops=1)
               Buffers: shared hit=270937 read=1137996
               ->  Hash Join  (cost=397317.03..1146940.27 rows=560033 width=176) (actual time=5100.961..23077.036 rows=1148681 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=270937 read=1137996
                     ->  Hash Join  (cost=397315.47..1139238.25 rows=560033 width=154) (actual time=5100.918..22697.770 rows=1148681 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=270936 read=1137996
                           ->  Merge Join  (cost=328287.47..1059009.59 rows=560033 width=12) (actual time=2734.898..17704.663 rows=1148681 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=270934 read=1102720
                                 ->  Sort  (cost=328287.45..329705.76 rows=567324 width=8) (actual time=2734.730..2860.134 rows=573681 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51468kB
                                       Buffers: shared hit=38609 read=191298
                                       ->  Bitmap Heap Scan on orders  (cost=12036.97..274068.83 rows=567324 width=8) (actual time=223.940..2533.678 rows=573681 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Buffers: shared hit=38609 read=191298
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11895.14 rows=567324 width=0) (actual time=161.034..161.034 rows=573681 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1570
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..685230.16 rows=14822016 width=12) (actual time=0.111..12963.953 rows=14822972 loops=1)
                                       Buffers: shared hit=232325 read=911422
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2363.873..2363.873 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=0.004..698.931 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.024..0.024 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=0.010..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 25553.634 ms
(40 rows)

COMMIT;
COMMIT