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 '1993-12-01'
	and o_orderdate < cast(date '1993-12-01' + 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=1148786.38..1148786.43 rows=20 width=175) (actual time=25336.909..25336.918 rows=20 loops=1)
   Buffers: shared hit=871098 read=547071 dirtied=763 written=2037
   ->  Sort  (cost=1148786.38..1150161.18 rows=549922 width=175) (actual time=25336.905..25336.911 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=871098 read=547071 dirtied=763 written=2037
         ->  HashAggregate  (cost=1128653.93..1134153.15 rows=549922 width=175) (actual time=24910.767..25198.206 rows=374982 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=871095 read=547071 dirtied=763 written=2037
               ->  Hash Join  (cost=350735.16..1114905.88 rows=549922 width=175) (actual time=4014.753..22563.111 rows=1121261 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=871095 read=547071 dirtied=763 written=2037
                     ->  Hash Join  (cost=350733.60..1107342.89 rows=549922 width=153) (actual time=4014.705..22175.099 rows=1121261 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=871094 read=547071 dirtied=763 written=2037
                           ->  Hash Join  (cost=281705.60..1030066.06 rows=549922 width=12) (actual time=2302.763..19519.769 rows=1121261 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=839331 read=543556 dirtied=763 written=2037
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..687144.40 rows=14857941 width=12) (actual time=0.079..13561.197 rows=14823489 loops=1)
                                       Buffers: shared hit=651884 read=501665 dirtied=542 written=2037
                                 ->  Hash  (cost=274730.75..274730.75 rows=557953 width=8) (actual time=2294.929..2294.929 rows=560913 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30103kB
                                       Buffers: shared hit=187447 read=41891 dirtied=221
                                       ->  Bitmap Heap Scan on orders  (cost=11827.45..274730.75 rows=557953 width=8) (actual time=288.410..2107.181 rows=560913 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-12-01'::date) AND (o_orderdate < '1994-03-01'::date))
                                             Heap Blocks: exact=227802
                                             Buffers: shared hit=187447 read=41891 dirtied=221
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11687.96 rows=557953 width=0) (actual time=205.838..205.838 rows=563212 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-12-01'::date) AND (o_orderdate < '1994-03-01'::date))
                                                   Buffers: shared read=1536
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1676.486..1676.486 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=31763 read=3515
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.026..714.516 rows=1500000 loops=1)
                                       Buffers: shared hit=31763 read=3515
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.026..0.026 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=0.010..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.270 ms
 Execution time: 25370.321 ms
(42 rows)

COMMIT;
COMMIT