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=1186949.07..1186949.12 rows=20 width=176) (actual time=38972.888..38972.898 rows=20 loops=1)
   Buffers: shared hit=635742 read=789413 dirtied=956 written=47795
   ->  Sort  (cost=1186949.07..1188323.69 rows=549851 width=176) (actual time=38972.882..38972.888 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=635742 read=789413 dirtied=956 written=47795
         ->  HashAggregate  (cost=1166819.22..1172317.73 rows=549851 width=176) (actual time=38449.011..38797.483 rows=371269 loops=1)
               Buffers: shared hit=635739 read=789413 dirtied=956 written=47795
               ->  Hash Join  (cost=398188.68..1153072.94 rows=549851 width=176) (actual time=4554.579..34427.001 rows=1080012 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=635739 read=789413 dirtied=956 written=47795
                     ->  Hash Join  (cost=398187.12..1145510.93 rows=549851 width=154) (actual time=4554.529..33735.665 rows=1080012 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=635738 read=789413 dirtied=956 written=47795
                           ->  Merge Join  (cost=329159.12..1065485.91 rows=549851 width=12) (actual time=2507.579..29385.667 rows=1080012 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=600460 read=789413 dirtied=956 written=47795
                                 ->  Sort  (cost=329159.10..330551.65 rows=557021 width=8) (actual time=2507.275..2706.580 rows=561774 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50910kB
                                       Buffers: shared hit=228879 read=1619
                                       ->  Bitmap Heap Scan on orders  (cost=12095.45..275998.76 rows=557021 width=8) (actual time=387.733..2236.272 rows=561774 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Buffers: shared hit=228879 read=1619
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11956.19 rows=557021 width=0) (actual time=286.134..286.134 rows=566313 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                                   Buffers: shared read=1619
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..690692.79 rows=14940165 width=12) (actual time=0.118..23276.555 rows=14822843 loops=1)
                                       Buffers: shared hit=371581 read=787794 dirtied=956 written=47795
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2044.396..2044.396 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.020..880.034 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.028..0.028 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.007..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 39024.156 ms
(40 rows)

COMMIT;
COMMIT