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 '1994-01-01'
	and o_orderdate < cast(date '1994-01-01' + 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=1149795.36..1149795.41 rows=20 width=175) (actual time=23436.574..23436.580 rows=20 loops=1)
   Buffers: shared hit=1360376 read=56839 written=123
   ->  Sort  (cost=1149795.36..1151188.06 rows=557077 width=175) (actual time=23436.570..23436.575 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=1360376 read=56839 written=123
         ->  HashAggregate  (cost=1129400.97..1134971.74 rows=557077 width=175) (actual time=22932.378..23286.820 rows=374874 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=1360373 read=56839 written=123
               ->  Hash Join  (cost=350490.74..1115474.05 rows=557077 width=175) (actual time=3673.469..20386.286 rows=1120579 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1360373 read=56839 written=123
                     ->  Hash Join  (cost=350489.18..1107812.68 rows=557077 width=153) (actual time=3673.432..20000.431 rows=1120579 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1360372 read=56839 written=123
                           ->  Hash Join  (cost=281461.18..1030428.52 rows=557077 width=12) (actual time=2026.158..17437.503 rows=1120579 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=1325094 read=56839 written=123
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..687611.55 rows=14876121 width=12) (actual time=0.030..11067.387 rows=14808453 loops=1)
                                       Buffers: shared hit=1103367 read=49651 written=21
                                 ->  Hash  (cost=274418.26..274418.26 rows=563399 width=8) (actual time=2019.217..2019.217 rows=560126 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30072kB
                                       Buffers: shared hit=221727 read=7188 written=102
                                       ->  Bitmap Heap Scan on orders  (cost=11939.27..274418.26 rows=563399 width=8) (actual time=312.250..1806.526 rows=560126 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Heap Blocks: exact=227382
                                             Buffers: shared hit=221727 read=7188 written=102
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11798.42 rows=563399 width=0) (actual time=222.023..222.023 rows=562377 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared hit=591 read=942 written=82
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1634.153..1634.153 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..680.171 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=0.008..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.317 ms
 Execution time: 23466.078 ms
(42 rows)

COMMIT;
COMMIT