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=1155018.00..1155018.05 rows=20 width=176) (actual time=21851.531..21851.539 rows=20 loops=1)
   Buffers: shared hit=820684 read=601752 dirtied=1580 written=416
   ->  Sort  (cost=1155018.00..1156440.05 rows=568820 width=176) (actual time=21851.527..21851.530 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=820684 read=601752 dirtied=1580 written=416
         ->  HashAggregate  (cost=1134193.70..1139881.90 rows=568820 width=176) (actual time=21522.527..21719.903 rows=381138 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=820681 read=601752 dirtied=1580 written=416
               ->  Hash Join  (cost=353023.03..1119973.20 rows=568820 width=176) (actual time=2945.372..19466.815 rows=1147595 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=820681 read=601752 dirtied=1580 written=416
                     ->  Hash Join  (cost=353021.46..1112150.36 rows=568820 width=154) (actual time=2945.328..19102.346 rows=1147595 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=820680 read=601752 dirtied=1580 written=416
                           ->  Hash Join  (cost=283993.46..1034590.06 rows=568820 width=12) (actual time=1526.852..17011.527 rows=1147595 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=785402 read=601752 dirtied=1580 written=416
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..689056.88 rows=14893854 width=12) (actual time=0.077..12292.968 rows=14807964 loops=1)
                                       Buffers: shared hit=555206 read=600101 dirtied=1580 written=416
                                 ->  Hash  (cost=276767.67..276767.67 rows=578029 width=8) (actual time=1521.190..1521.190 rows=573106 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30579kB
                                       Buffers: shared hit=230196 read=1651
                                       ->  Bitmap Heap Scan on orders  (cost=12549.23..276767.67 rows=578029 width=8) (actual time=221.022..1363.088 rows=573106 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Heap Blocks: exact=230196
                                             Buffers: shared hit=230196 read=1651
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12404.73 rows=578029 width=0) (actual time=156.347..156.347 rows=578249 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1651
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1409.709..1409.709 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=146) (actual time=0.025..629.471 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.028..0.028 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=0.011..0.015 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.026 ms
 Execution time: 21875.397 ms
(42 rows)

COMMIT;
COMMIT