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 '1994-03-01'
	and o_orderdate < cast(date '1994-03-01' + 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=1187081.25..1187081.30 rows=20 width=176) (actual time=42950.034..42950.041 rows=20 loops=1)
   Buffers: shared hit=699956 read=724312 dirtied=1306 written=135
   ->  Sort  (cost=1187081.25..1188488.32 rows=562827 width=176) (actual time=42950.030..42950.033 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=699956 read=724312 dirtied=1306 written=135
         ->  HashAggregate  (cost=1166476.36..1172104.63 rows=562827 width=176) (actual time=42413.734..42779.049 rows=381357 loops=1)
               Buffers: shared hit=699953 read=724312 dirtied=1306 written=135
               ->  Hash Join  (cost=399040.44..1152405.68 rows=562827 width=176) (actual time=6295.580..37726.273 rows=1148648 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=699953 read=724312 dirtied=1306 written=135
                     ->  Hash Join  (cost=399038.88..1144665.25 rows=562827 width=154) (actual time=6295.540..36957.983 rows=1148648 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=699952 read=724312 dirtied=1306 written=135
                           ->  Merge Join  (cost=330010.88..1064380.71 rows=562827 width=12) (actual time=3593.583..31221.678 rows=1148648 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=665306 read=723680 dirtied=1306 written=135
                                 ->  Sort  (cost=330010.86..331436.25 rows=570154 width=8) (actual time=3593.429..3799.868 rows=573629 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51465kB
                                       Buffers: shared hit=207733 read=23348 dirtied=231
                                       ->  Bitmap Heap Scan on orders  (cost=12162.00..275501.31 rows=570154 width=8) (actual time=619.842..3276.367 rows=573629 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Buffers: shared hit=207733 read=23348 dirtied=231
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12019.46 rows=570154 width=0) (actual time=483.300..483.300 rows=576514 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1588
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688650.82 rows=14895996 width=12) (actual time=0.110..23928.209 rows=14823256 loops=1)
                                       Buffers: shared hit=457573 read=700332 dirtied=1075 written=135
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2700.201..2700.201 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=34646 read=632
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.021..1154.708 rows=1500000 loops=1)
                                       Buffers: shared hit=34646 read=632
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.023..0.023 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=0.006..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 43037.616 ms
(40 rows)

COMMIT;
COMMIT