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=1152500.69..1152500.74 rows=20 width=175) (actual time=26297.634..26297.641 rows=20 loops=1)
   Buffers: shared hit=715100 read=703748 dirtied=115 written=19797
   ->  Sort  (cost=1152500.69..1153915.47 rows=565912 width=175) (actual time=26297.631..26297.635 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=715100 read=703748 dirtied=115 written=19797
         ->  HashAggregate  (cost=1131782.85..1137441.97 rows=565912 width=175) (actual time=25806.632..26138.164 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=715097 read=703748 dirtied=115 written=19797
               ->  Hash Join  (cost=351143.52..1117635.05 rows=565912 width=175) (actual time=5067.959..23750.626 rows=1150038 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=715097 read=703748 dirtied=115 written=19797
                     ->  Hash Join  (cost=351141.96..1109852.20 rows=565912 width=153) (actual time=5067.908..23358.885 rows=1150038 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=715096 read=703748 dirtied=115 written=19797
                           ->  Hash Join  (cost=282113.96..1032335.52 rows=565912 width=12) (actual time=3243.042..20771.846 rows=1150038 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=715089 read=668477 dirtied=115 written=19797
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..688666.09 rows=14905809 width=12) (actual time=0.078..14055.588 rows=14823114 loops=1)
                                       Buffers: shared hit=558644 read=594374 dirtied=115 written=19797
                                 ->  Hash  (cost=274966.48..274966.48 rows=571764 width=8) (actual time=3236.153..3236.153 rows=574594 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30638kB
                                       Buffers: shared hit=156445 read=74103
                                       ->  Bitmap Heap Scan on orders  (cost=12109.02..274966.48 rows=571764 width=8) (actual time=862.943..3042.773 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=156445 read=74103
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11966.07 rows=571764 width=0) (actual time=760.566..760.566 rows=576360 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared read=1571
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1810.263..1810.263 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=7 read=35271
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.011..941.673 rows=1500000 loops=1)
                                       Buffers: shared hit=7 read=35271
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.034..0.034 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=0.005..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.312 ms
 Execution time: 26329.987 ms
(42 rows)

COMMIT;
COMMIT