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=1188708.89..1188708.94 rows=20 width=175) (actual time=75988.509..75988.517 rows=20 loops=1)
   Buffers: shared hit=549373 read=879450 dirtied=837 written=176
   ->  Sort  (cost=1188708.89..1190083.70 rows=549924 width=175) (actual time=75988.506..75988.512 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=549373 read=879450 dirtied=837 written=176
         ->  HashAggregate  (cost=1168576.37..1174075.61 rows=549924 width=175) (actual time=75454.575..75822.075 rows=371197 loops=1)
               Buffers: shared hit=549370 read=879450 dirtied=837 written=176
               ->  Hash Join  (cost=399973.73..1154828.27 rows=549924 width=175) (actual time=15283.040..70630.379 rows=1079903 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=549370 read=879450 dirtied=837 written=176
                     ->  Hash Join  (cost=399972.17..1147265.25 rows=549924 width=153) (actual time=15283.000..69763.338 rows=1079903 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=549369 read=879450 dirtied=837 written=176
                           ->  Merge Join  (cost=330944.17..1067238.77 rows=549924 width=12) (actual time=12185.862..64133.920 rows=1079903 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=514091 read=879450 dirtied=837 written=176
                                 ->  Sort  (cost=330944.15..332345.93 rows=560711 width=8) (actual time=12185.614..12408.858 rows=561695 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50906kB
                                       Buffers: shared hit=104187 read=127458 written=4
                                       ->  Bitmap Heap Scan on orders  (cost=12181.28..277404.95 rows=560711 width=8) (actual time=684.524..11850.288 rows=561695 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Buffers: shared hit=104187 read=127458 written=4
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12041.10 rows=560711 width=0) (actual time=578.449..578.449 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..690698.60 rows=14917296 width=12) (actual time=0.122..47963.584 rows=14822460 loops=1)
                                       Buffers: shared hit=409904 read=751992 dirtied=837 written=172
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3094.948..3094.948 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=145) (actual time=0.015..1742.063 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  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: 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: 76045.572 ms
(40 rows)

COMMIT;
COMMIT