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=1157640.37..1157640.42 rows=20 width=176) (actual time=27093.664..27093.705 rows=20 loops=1)
   Buffers: shared hit=774382 read=649784 written=14906
   ->  Sort  (cost=1157640.37..1159063.58 rows=569285 width=176) (actual time=27093.661..27093.696 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=774382 read=649784 written=14906
         ->  HashAggregate  (cost=1136799.05..1142491.90 rows=569285 width=176) (actual time=26440.048..26934.489 rows=381472 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=774379 read=649784 written=14906
               ->  Hash Join  (cost=353528.69..1122566.92 rows=569285 width=176) (actual time=3646.190..24013.668 rows=1148919 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=774379 read=649784 written=14906
                     ->  Hash Join  (cost=353527.12..1114737.69 rows=569285 width=154) (actual time=3646.151..23594.892 rows=1148919 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=774378 read=649784 written=14906
                           ->  Hash Join  (cost=284499.12..1037170.42 rows=569285 width=12) (actual time=2130.851..21047.629 rows=1148919 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=744944 read=643940 written=14898
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..690959.45 rows=14938515 width=12) (actual time=0.070..14422.728 rows=14822651 loops=1)
                                       Buffers: shared hit=542519 read=614062 written=14863
                                 ->  Hash  (cost=277274.76..277274.76 rows=577914 width=8) (actual time=2125.142..2125.142 rows=573731 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30604kB
                                       Buffers: shared hit=202425 read=29878 written=35
                                       ->  Bitmap Heap Scan on orders  (cost=12552.05..277274.76 rows=577914 width=8) (actual time=292.273..1941.370 rows=573731 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Heap Blocks: exact=230645
                                             Buffers: shared hit=202425 read=29878 written=35
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12407.57 rows=577914 width=0) (actual time=213.971..213.971 rows=579410 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1658 written=2
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1503.657..1503.657 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=29434 read=5844 written=8
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.015..681.513 rows=1500000 loops=1)
                                       Buffers: shared hit=29434 read=5844 written=8
                     ->  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=0.009..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.317 ms
 Execution time: 27121.054 ms
(42 rows)

COMMIT;
COMMIT