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=1192520.63..1192520.68 rows=20 width=176) (actual time=41934.524..41934.534 rows=20 loops=1)
   Buffers: shared hit=621965 read=806858 dirtied=1130 written=260
   ->  Sort  (cost=1192520.63..1193902.09 rows=552584 width=176) (actual time=41934.518..41934.523 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=621965 read=806858 dirtied=1130 written=260
         ->  HashAggregate  (cost=1172290.73..1177816.57 rows=552584 width=176) (actual time=41277.350..41692.258 rows=371197 loops=1)
               Buffers: shared hit=621962 read=806858 dirtied=1130 written=260
               ->  Hash Join  (cost=399842.36..1158476.13 rows=552584 width=176) (actual time=9083.145..37225.765 rows=1079903 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=621962 read=806858 dirtied=1130 written=260
                     ->  Hash Join  (cost=399840.80..1150876.54 rows=552584 width=154) (actual time=9083.095..36522.957 rows=1079903 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=621961 read=806858 dirtied=1130 written=260
                           ->  Merge Join  (cost=330812.80..1070796.86 rows=552584 width=12) (actual time=5237.091..30005.496 rows=1079903 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=621959 read=771582 dirtied=1130 written=83
                                 ->  Sort  (cost=330812.78..332212.23 rows=559778 width=8) (actual time=5236.764..5429.330 rows=561695 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50906kB
                                       Buffers: shared hit=116920 read=114725 dirtied=222 written=4
                                       ->  Bitmap Heap Scan on orders  (cost=12159.72..277369.39 rows=559778 width=8) (actual time=322.723..4553.785 rows=561695 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Buffers: shared hit=116920 read=114725 dirtied=222 written=4
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12019.77 rows=559778 width=0) (actual time=237.139..237.139 rows=569171 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                                   Buffers: shared read=1631
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694123.30 rows=15014422 width=12) (actual time=0.165..21203.660 rows=14822460 loops=1)
                                       Buffers: shared hit=505039 read=656857 dirtied=908 written=79
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=3844.026..3844.026 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=2 read=35276 written=177
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.021..1538.941 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276 written=177
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.029..0.029 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=0.008..0.015 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 42040.762 ms
(40 rows)

COMMIT;
COMMIT