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=1195333.65..1195333.70 rows=20 width=175) (actual time=29051.867..29051.873 rows=20 loops=1)
   Buffers: shared hit=1299807 read=123513 dirtied=339 written=3099
   ->  Sort  (cost=1195333.65..1196786.50 rows=581139 width=175) (actual time=29051.863..29051.867 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=1299807 read=123513 dirtied=339 written=3099
         ->  HashAggregate  (cost=1174058.36..1179869.75 rows=581139 width=175) (actual time=28583.966..28896.452 rows=381471 loops=1)
               Buffers: shared hit=1299804 read=123513 dirtied=339 written=3099
               ->  Hash Join  (cost=402956.08..1159529.89 rows=581139 width=175) (actual time=5649.565..25032.599 rows=1148508 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1299804 read=123513 dirtied=339 written=3099
                     ->  Hash Join  (cost=402954.52..1151537.66 rows=581139 width=153) (actual time=5649.512..24346.927 rows=1148508 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1299803 read=123513 dirtied=339 written=3099
                           ->  Merge Join  (cost=333926.52..1070886.88 rows=581139 width=12) (actual time=3303.142..19884.284 rows=1148508 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1264532 read=123506 dirtied=339 written=3099
                                 ->  Sort  (cost=333918.96..335392.21 rows=589298 width=8) (actual time=3303.004..3476.223 rows=573887 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51477kB
                                       Buffers: shared hit=170262 read=61699 dirtied=225
                                       ->  Bitmap Heap Scan on orders  (cost=12798.29..277438.76 rows=589298 width=8) (actual time=668.975..3058.062 rows=573887 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                             Buffers: shared hit=170262 read=61699 dirtied=225
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12650.97 rows=589298 width=0) (actual time=494.131..494.131 rows=578953 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                                   Buffers: shared hit=2 read=1655
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..690859.54 rows=14940208 width=12) (actual time=0.117..13124.458 rows=14822772 loops=1)
                                       Buffers: shared hit=1094270 read=61807 dirtied=114 written=3099
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2344.226..2344.226 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35271 read=7
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.019..1041.193 rows=1500000 loops=1)
                                       Buffers: shared hit=35271 read=7
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.034..0.034 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=0.011..0.015 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 29093.458 ms
(40 rows)

COMMIT;
COMMIT