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 '1993-09-01'
	and o_orderdate < cast(date '1993-09-01' + 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=1155758.15..1155758.20 rows=20 width=175) (actual time=19997.610..19997.624 rows=20 loops=1)
   Buffers: shared hit=1265194 read=155964 written=170
   ->  Sort  (cost=1155758.15..1157174.15 rows=566400 width=175) (actual time=19997.608..19997.612 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=1265194 read=155964 written=170
         ->  HashAggregate  (cost=1135022.45..1140686.45 rows=566400 width=175) (actual time=19612.692..19859.014 rows=378890 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=1265191 read=155964 written=170
               ->  Hash Join  (cost=352518.11..1120862.45 rows=566400 width=175) (actual time=3788.295..17772.432 rows=1136419 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1265191 read=155964 written=170
                     ->  Hash Join  (cost=352516.55..1113072.88 rows=566400 width=153) (actual time=3788.255..17389.540 rows=1136419 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1265190 read=155964 written=170
                           ->  Hash Join  (cost=283488.55..1035548.88 rows=566400 width=12) (actual time=2285.515..15172.215 rows=1136419 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=1229912 read=155964 written=170
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..690386.01 rows=14936204 width=12) (actual time=0.071..9457.276 rows=14823054 loops=1)
                                       Buffers: shared hit=1043686 read=111334 written=113
                                 ->  Hash  (cost=276321.00..276321.00 rows=573369 width=8) (actual time=2279.370..2279.370 rows=567958 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30378kB
                                       Buffers: shared hit=186226 read=44630 written=57
                                       ->  Bitmap Heap Scan on orders  (cost=12425.47..276321.00 rows=573369 width=8) (actual time=294.940..2079.026 rows=567958 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-09-01'::date) AND (o_orderdate < '1993-12-01'::date))
                                             Heap Blocks: exact=229228
                                             Buffers: shared hit=186226 read=44630 written=57
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12282.12 rows=573369 width=0) (actual time=213.939..213.939 rows=571833 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-09-01'::date) AND (o_orderdate < '1993-12-01'::date))
                                                   Buffers: shared hit=1 read=1627 written=3
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1491.180..1491.180 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.016..667.656 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  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: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.006..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.432 ms
 Execution time: 20023.033 ms
(42 rows)

COMMIT;
COMMIT