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=1154211.59..1154211.64 rows=20 width=175) (actual time=22903.184..22903.190 rows=20 loops=1)
   Buffers: shared hit=1031635 read=393816 dirtied=116 written=860
   ->  Sort  (cost=1154211.59..1155622.95 rows=564545 width=175) (actual time=22903.181..22903.186 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=1031635 read=393816 dirtied=116 written=860
         ->  HashAggregate  (cost=1133543.80..1139189.25 rows=564545 width=175) (actual time=22508.343..22765.645 rows=378851 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=1031632 read=393816 dirtied=116 written=860
               ->  Hash Join  (cost=352488.71..1119430.18 rows=564545 width=175) (actual time=3821.117..20364.994 rows=1137101 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1031632 read=393816 dirtied=116 written=860
                     ->  Hash Join  (cost=352487.15..1111666.12 rows=564545 width=153) (actual time=3820.921..19973.236 rows=1137101 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1031631 read=393816 dirtied=116 written=860
                           ->  Hash Join  (cost=283459.15..1034169.95 rows=564545 width=12) (actual time=2046.149..17337.091 rows=1137101 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=1031629 read=358540 dirtied=116 written=843
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..689183.14 rows=14902040 width=12) (actual time=0.058..11531.066 rows=14823054 loops=1)
                                       Buffers: shared hit=818811 read=340097 dirtied=116 written=838
                                 ->  Hash  (cost=276298.69..276298.69 rows=572802 width=8) (actual time=2038.645..2038.645 rows=568417 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30396kB
                                       Buffers: shared hit=212818 read=18443 written=5
                                       ->  Bitmap Heap Scan on orders  (cost=12411.66..276298.69 rows=572802 width=8) (actual time=275.051..1805.316 rows=568417 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                             Heap Blocks: exact=229628
                                             Buffers: shared hit=212818 read=18443 written=5
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12268.45 rows=572802 width=0) (actual time=197.225..197.225 rows=572378 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                                   Buffers: shared read=1633 written=5
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1760.874..1760.874 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276 written=17
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.010..848.374 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276 written=17
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.019..0.019 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=0.006..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.382 ms
 Execution time: 22927.218 ms
(42 rows)

COMMIT;
COMMIT