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 '1993-10-01'
	and o_orderdate < cast(date '1993-10-01' + 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=1157331.85..1157331.90 rows=20 width=175) (actual time=24641.585..24641.602 rows=20 loops=1)
   Buffers: shared hit=831975 read=595930 dirtied=329 written=933
   ->  Sort  (cost=1157331.85..1158745.00 rows=565261 width=175) (actual time=24641.583..24641.595 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=831975 read=595930 dirtied=329 written=933
         ->  HashAggregate  (cost=1136637.84..1142290.45 rows=565261 width=175) (actual time=24113.151..24489.552 rows=381460 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=831972 read=595930 dirtied=329 written=933
               ->  Hash Join  (cost=353310.93..1122506.32 rows=565261 width=175) (actual time=4766.862..22165.412 rows=1148455 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=831972 read=595930 dirtied=329 written=933
                     ->  Hash Join  (cost=353309.36..1114732.42 rows=565261 width=153) (actual time=4766.829..21777.586 rows=1148455 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=831971 read=595930 dirtied=329 written=933
                           ->  Hash Join  (cost=284281.36..1037225.50 rows=565261 width=12) (actual time=3312.079..19469.300 rows=1148455 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=797195 read=595428 dirtied=329 written=932
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..691242.70 rows=14946472 width=12) (actual time=0.076..12147.983 rows=14822651 loops=1)
                                       Buffers: shared hit=623921 read=536519 dirtied=114 written=877
                                 ->  Hash  (cost=277111.89..277111.89 rows=573523 width=8) (actual time=2675.791..2675.791 rows=573892 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30610kB
                                       Buffers: shared hit=173274 read=58909 dirtied=215 written=55
                                       ->  Bitmap Heap Scan on orders  (cost=12455.05..277111.89 rows=573523 width=8) (actual time=812.134..2467.129 rows=573892 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                             Heap Blocks: exact=230527
                                             Buffers: shared hit=173274 read=58909 dirtied=215 written=55
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12311.66 rows=573523 width=0) (actual time=725.812..725.812 rows=579534 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                                   Buffers: shared read=1656 written=4
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1443.221..1443.221 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=34776 read=502 written=1
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.016..607.896 rows=1500000 loops=1)
                                       Buffers: shared hit=34776 read=502 written=1
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.020..0.020 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..0.008 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.305 ms
 Execution time: 24673.493 ms
(42 rows)

COMMIT;
COMMIT