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 '1994-06-01'
	and o_orderdate < cast(date '1994-06-01' + 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=1189999.69..1189999.74 rows=20 width=175) (actual time=27659.757..27659.767 rows=20 loops=1)
   Buffers: shared hit=1062485 read=362523 dirtied=230 written=683
   ->  Sort  (cost=1189999.69..1191429.66 rows=571988 width=175) (actual time=27659.753..27659.758 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=1062485 read=362523 dirtied=230 written=683
         ->  HashAggregate  (cost=1169059.42..1174779.30 rows=571988 width=175) (actual time=27093.803..27492.354 rows=382099 loops=1)
               Buffers: shared hit=1062482 read=362523 dirtied=230 written=683
               ->  Hash Join  (cost=400793.46..1154759.72 rows=571988 width=175) (actual time=4950.209..23964.557 rows=1149798 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1062482 read=362523 dirtied=230 written=683
                     ->  Hash Join  (cost=400791.89..1146893.32 rows=571988 width=153) (actual time=4950.176..23391.987 rows=1149798 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1062481 read=362523 dirtied=230 written=683
                           ->  Merge Join  (cost=331763.89..1066425.56 rows=571988 width=12) (actual time=2160.624..18123.424 rows=1149798 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1027203 read=362523 dirtied=230 written=683
                                 ->  Sort  (cost=331756.39..333206.43 rows=580015 width=8) (actual time=2160.487..2312.383 rows=574833 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51522kB
                                       Buffers: shared hit=219293 read=12010 dirtied=230
                                       ->  Bitmap Heap Scan on orders  (cost=12491.11..276232.33 rows=580015 width=8) (actual time=277.482..1887.385 rows=574833 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                             Buffers: shared hit=219293 read=12010 dirtied=230
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12346.10 rows=580015 width=0) (actual time=199.291..199.291 rows=578357 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                                   Buffers: shared hit=106 read=1532
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688809.44 rows=14895917 width=12) (actual time=0.112..13107.062 rows=14822923 loops=1)
                                       Buffers: shared hit=807910 read=350513 written=683
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2787.555..2787.555 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.011..657.113 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.019..0.019 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.005..0.007 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 27732.315 ms
(40 rows)

COMMIT;
COMMIT