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=1149488.36..1149488.41 rows=20 width=175) (actual time=31801.009..31801.016 rows=20 loops=1)
   Buffers: shared hit=686698 read=732149 dirtied=136 written=11
   ->  Sort  (cost=1149488.36..1150891.73 rows=561349 width=175) (actual time=31801.005..31801.008 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=686698 read=732149 dirtied=136 written=11
         ->  HashAggregate  (cost=1128937.58..1134551.07 rows=561349 width=175) (actual time=31228.002..31643.569 rows=381821 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=686695 read=732149 dirtied=136 written=11
               ->  Hash Join  (cost=351036.02..1114903.85 rows=561349 width=175) (actual time=4127.517..23966.154 rows=1150038 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=686695 read=732149 dirtied=136 written=11
                     ->  Hash Join  (cost=351034.46..1107183.74 rows=561349 width=153) (actual time=4127.475..23570.722 rows=1150038 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=686694 read=732149 dirtied=136 written=11
                           ->  Hash Join  (cost=282006.46..1029735.51 rows=561349 width=12) (actual time=2575.782..20978.435 rows=1150038 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=651506 read=732059 dirtied=136 written=11
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686454.60 rows=14843038 width=12) (actual time=0.064..13593.343 rows=14823114 loops=1)
                                       Buffers: shared hit=478746 read=674271 written=11
                                 ->  Hash  (cost=274886.62..274886.62 rows=569552 width=8) (actual time=2563.925..2563.925 rows=574594 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30638kB
                                       Buffers: shared hit=172760 read=57788 dirtied=136
                                       ->  Bitmap Heap Scan on orders  (cost=12062.34..274886.62 rows=569552 width=8) (actual time=447.258..2319.676 rows=574594 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Heap Blocks: exact=228977
                                             Buffers: shared hit=172760 read=57788 dirtied=136
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11919.95 rows=569552 width=0) (actual time=326.977..326.977 rows=576360 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared hit=1 read=1570
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1536.179..1536.179 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=35188 read=90
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.012..630.097 rows=1500000 loops=1)
                                       Buffers: shared hit=35188 read=90
                     ->  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: 3.712 ms
 Execution time: 31838.588 ms
(42 rows)

COMMIT;
COMMIT