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 '1994-05-01'
	and o_orderdate < cast(date '1994-05-01' + 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=1153350.54..1153350.59 rows=20 width=175) (actual time=30938.707..30938.717 rows=20 loops=1)
   Buffers: shared hit=889103 read=539491 dirtied=699 written=5893
   ->  Sort  (cost=1153350.54..1154758.11 rows=563027 width=175) (actual time=30938.704..30938.711 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=889103 read=539491 dirtied=699 written=5893
         ->  HashAggregate  (cost=1132738.32..1138368.59 rows=563027 width=175) (actual time=30346.699..30774.676 rows=381487 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=889100 read=539491 dirtied=699 written=5893
               ->  Hash Join  (cost=351636.70..1118662.65 rows=563027 width=175) (actual time=4845.168..23657.753 rows=1148755 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=889100 read=539491 dirtied=699 written=5893
                     ->  Hash Join  (cost=351635.14..1110919.46 rows=563027 width=153) (actual time=4845.130..23258.067 rows=1148755 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=889099 read=539491 dirtied=699 written=5893
                           ->  Hash Join  (cost=282607.14..1033446.06 rows=563027 width=12) (actual time=3157.201..20716.468 rows=1148755 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=853821 read=539491 dirtied=699 written=5893
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..689287.56 rows=14912407 width=12) (actual time=0.085..13002.895 rows=14808418 loops=1)
                                       Buffers: shared hit=722162 read=440125 dirtied=699 written=613
                                 ->  Hash  (cost=275485.09..275485.09 rows=569729 width=8) (actual time=3148.875..3148.875 rows=573969 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30613kB
                                       Buffers: shared hit=131659 read=99366 written=5280
                                       ->  Bitmap Heap Scan on orders  (cost=12152.16..275485.09 rows=569729 width=8) (actual time=411.910..2905.611 rows=573969 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Heap Blocks: exact=229426
                                             Buffers: shared hit=131659 read=99366 written=5280
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12009.73 rows=569729 width=0) (actual time=298.358..298.358 rows=577507 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared read=1599 written=106
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1675.919..1675.919 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=0.017..710.872 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.023..0.023 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=0.007..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.670 ms
 Execution time: 30961.799 ms
(42 rows)

COMMIT;
COMMIT