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 '1994-12-01'
	and o_orderdate < cast(date '1994-12-01' + 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=1147946.27..1147946.32 rows=20 width=175) (actual time=34794.908..34794.919 rows=20 loops=1)
   Buffers: shared hit=718876 read=694727 written=4665
   ->  Sort  (cost=1147946.27..1149333.89 rows=555048 width=175) (actual time=34794.904..34794.912 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=718876 read=694727 written=4665
         ->  HashAggregate  (cost=1127626.16..1133176.64 rows=555048 width=175) (actual time=34209.760..34634.316 rows=371083 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=718873 read=694727 written=4665
               ->  Hash Join  (cost=350458.81..1113749.96 rows=555048 width=175) (actual time=4935.078..27814.920 rows=1079251 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=718873 read=694727 written=4665
                     ->  Hash Join  (cost=350457.25..1106116.48 rows=555048 width=153) (actual time=4935.037..27397.624 rows=1079251 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=718872 read=694727 written=4665
                           ->  Hash Join  (cost=281429.25..1028762.76 rows=555048 width=12) (actual time=2913.856..24092.672 rows=1079251 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=718870 read=659451 written=4665
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686138.58 rows=14838637 width=12) (actual time=0.074..15386.043 rows=14808453 loops=1)
                                       Buffers: shared hit=571315 read=577956 written=4352
                                 ->  Hash  (cost=274394.25..274394.25 rows=562765 width=8) (actual time=2905.955..2905.955 rows=561282 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30118kB
                                       Buffers: shared hit=147555 read=81495 written=313
                                       ->  Bitmap Heap Scan on orders  (cost=11924.78..274394.25 rows=562765 width=8) (actual time=323.718..2690.889 rows=561282 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Heap Blocks: exact=227514
                                             Buffers: shared hit=147555 read=81495 written=313
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11784.09 rows=562765 width=0) (actual time=232.130..232.130 rows=562978 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                                   Buffers: shared read=1536
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2006.805..2006.805 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.014..1032.536 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  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..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.487 ms
 Execution time: 34822.850 ms
(42 rows)

COMMIT;
COMMIT