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 '1994-09-01'
	and o_orderdate < cast(date '1994-09-01' + 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=1161113.59..1161113.64 rows=20 width=175) (actual time=25022.067..25022.074 rows=20 loops=1)
   Buffers: shared hit=790557 read=637102 dirtied=286 written=741
   ->  Sort  (cost=1161113.59..1162550.68 rows=574833 width=175) (actual time=25022.062..25022.067 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=790557 read=637102 dirtied=286 written=741
         ->  HashAggregate  (cost=1140069.16..1145817.49 rows=574833 width=175) (actual time=24541.522..24871.959 rows=378848 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=790554 read=637102 dirtied=286 written=741
               ->  Hash Join  (cost=353668.84..1125698.34 rows=574833 width=175) (actual time=3732.084..22264.445 rows=1136943 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=790554 read=637102 dirtied=286 written=741
                     ->  Hash Join  (cost=353667.28..1117792.82 rows=574833 width=153) (actual time=3732.038..21874.658 rows=1136943 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=790553 read=637102 dirtied=286 written=741
                           ->  Hash Join  (cost=284639.28..1040142.33 rows=574833 width=12) (actual time=2197.670..19424.842 rows=1136943 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=755276 read=637101 dirtied=286 written=741
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..693468.85 rows=15009681 width=12) (actual time=0.072..13000.180 rows=14822651 loops=1)
                                       Buffers: shared hit=574991 read=585450 dirtied=114 written=457
                                 ->  Hash  (cost=277379.10..277379.10 rows=580779 width=8) (actual time=2191.419..2191.419 rows=568354 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30394kB
                                       Buffers: shared hit=180285 read=51651 dirtied=172 written=284
                                       ->  Bitmap Heap Scan on orders  (cost=12613.42..277379.10 rows=580779 width=8) (actual time=282.908..2003.434 rows=568354 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                             Heap Blocks: exact=230293
                                             Buffers: shared hit=180285 read=51651 dirtied=172 written=284
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12468.23 rows=580779 width=0) (actual time=203.143..203.143 rows=574026 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                                   Buffers: shared hit=50 read=1593 written=52
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1522.518..1522.518 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=35277 read=1
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.017..677.285 rows=1500000 loops=1)
                                       Buffers: shared hit=35277 read=1
                     ->  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=0.007..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.320 ms
 Execution time: 25051.166 ms
(42 rows)

COMMIT;
COMMIT