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 '1993-12-01'
	and o_orderdate < cast(date '1993-12-01' + 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=1184406.71..1184406.76 rows=20 width=175) (actual time=35011.975..35011.981 rows=20 loops=1)
   Buffers: shared hit=1215206 read=210335 dirtied=12 written=2378
   ->  Sort  (cost=1184406.71..1185781.32 rows=549841 width=175) (actual time=35011.970..35011.973 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=1215206 read=210335 dirtied=12 written=2378
         ->  HashAggregate  (cost=1164277.23..1169775.64 rows=549841 width=175) (actual time=34457.972..34833.504 rows=374703 loops=1)
               Buffers: shared hit=1215203 read=210335 dirtied=12 written=2378
               ->  Hash Join  (cost=398621.88..1150531.21 rows=549841 width=175) (actual time=6853.647..31274.355 rows=1120171 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1215203 read=210335 dirtied=12 written=2378
                     ->  Hash Join  (cost=398620.31..1142969.33 rows=549841 width=153) (actual time=6853.601..30603.531 rows=1120171 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1215202 read=210335 dirtied=12 written=2378
                           ->  Merge Join  (cost=329592.31..1062944.51 rows=549841 width=12) (actual time=3979.411..25485.891 rows=1120171 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1179924 read=210335 dirtied=12 written=2378
                                 ->  Sort  (cost=329592.29..330992.61 rows=560126 width=8) (actual time=3979.188..4136.492 rows=560419 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50846kB
                                       Buffers: shared hit=227413 read=2908 written=245
                                       ->  Bitmap Heap Scan on orders  (cost=12163.28..276113.17 rows=560126 width=8) (actual time=630.540..3665.700 rows=560419 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-12-01'::date) AND (o_orderdate < '1994-03-01'::date))
                                             Buffers: shared hit=227413 read=2908 written=245
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12023.24 rows=560126 width=0) (actual time=515.348..515.348 rows=566070 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-12-01'::date) AND (o_orderdate < '1994-03-01'::date))
                                                   Buffers: shared hit=94 read=1526 written=156
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..687910.52 rows=14857064 width=12) (actual time=0.169..18328.406 rows=14807941 loops=1)
                                       Buffers: shared hit=952511 read=207427 dirtied=12 written=2133
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2872.054..2872.054 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=145) (actual time=0.015..1431.636 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=0.005..0.007 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 35056.236 ms
(40 rows)

COMMIT;
COMMIT