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 '1993-03-01'
	and o_orderdate < cast(date '1993-03-01' + 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=1195923.54..1195923.59 rows=20 width=175) (actual time=28081.265..28081.273 rows=20 loops=1)
   Buffers: shared hit=1379412 read=47752 dirtied=1702 written=1857
   ->  Sort  (cost=1195923.54..1197371.17 rows=579054 width=175) (actual time=28081.261..28081.266 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=1379412 read=47752 dirtied=1702 written=1857
         ->  HashAggregate  (cost=1174724.58..1180515.12 rows=579054 width=175) (actual time=27517.951..27885.142 rows=382285 loops=1)
               Buffers: shared hit=1379409 read=47752 dirtied=1702 written=1857
               ->  Hash Join  (cost=402461.45..1160248.23 rows=579054 width=175) (actual time=4615.227..24143.550 rows=1149524 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1379409 read=47752 dirtied=1702 written=1857
                     ->  Hash Join  (cost=402459.89..1152284.67 rows=579054 width=153) (actual time=4615.163..23457.478 rows=1149524 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1379408 read=47752 dirtied=1702 written=1857
                           ->  Merge Join  (cost=333431.89..1071675.59 rows=579054 width=12) (actual time=2282.333..18952.528 rows=1149524 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1348578 read=43304 dirtied=1702 written=1857
                                 ->  Sort  (cost=333431.89..334896.42 rows=585813 width=8) (actual time=2282.099..2453.159 rows=574055 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51485kB
                                       Buffers: shared hit=230285 read=1658 dirtied=449
                                       ->  Bitmap Heap Scan on orders  (cost=12722.57..277310.76 rows=585813 width=8) (actual time=381.292..2014.610 rows=574055 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-03-01'::date) AND (o_orderdate < '1993-06-01'::date))
                                             Buffers: shared hit=230285 read=1658 dirtied=449
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12576.12 rows=585813 width=0) (actual time=303.473..303.473 rows=579094 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-03-01'::date) AND (o_orderdate < '1993-06-01'::date))
                                                   Buffers: shared read=1658
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692088.41 rows=14975172 width=12) (actual time=0.153..13419.472 rows=14822760 loops=1)
                                       Buffers: shared hit=1118293 read=41646 dirtied=1253 written=1857
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2330.391..2330.391 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=30830 read=4448
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.082..1071.962 rows=1500000 loops=1)
                                       Buffers: shared hit=30830 read=4448
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.037..0.037 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=0.013..0.019 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 28129.103 ms
(40 rows)

COMMIT;
COMMIT