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=1195394.65..1195394.70 rows=20 width=175) (actual time=31636.424..31636.430 rows=20 loops=1)
   Buffers: shared hit=1232556 read=198272 dirtied=112 written=6663
   ->  Sort  (cost=1195394.65..1196841.94 rows=578915 width=175) (actual time=31636.418..31636.421 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=1232556 read=198272 dirtied=112 written=6663
         ->  HashAggregate  (cost=1174200.78..1179989.93 rows=578915 width=175) (actual time=31031.487..31436.433 rows=381988 loops=1)
               Buffers: shared hit=1232553 read=198272 dirtied=112 written=6663
               ->  Hash Join  (cost=402126.18..1159727.91 rows=578915 width=175) (actual time=5465.309..27292.876 rows=1148397 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1232553 read=198272 dirtied=112 written=6663
                     ->  Hash Join  (cost=402124.62..1151766.26 rows=578915 width=153) (actual time=5465.252..26555.195 rows=1148397 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1232552 read=198272 dirtied=112 written=6663
                           ->  Merge Join  (cost=333096.62..1071159.96 rows=578915 width=12) (actual time=2823.347..21708.766 rows=1148397 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1232549 read=162997 dirtied=112 written=6663
                                 ->  Sort  (cost=333096.62..334559.71 rows=585234 width=8) (actual time=2823.131..3011.992 rows=573516 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51460kB
                                       Buffers: shared hit=228946 read=2777
                                       ->  Bitmap Heap Scan on orders  (cost=12708.63..277035.14 rows=585234 width=8) (actual time=426.804..2534.345 rows=573516 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-03-01'::date) AND (o_orderdate < '1993-06-01'::date))
                                             Buffers: shared hit=228946 read=2777
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12562.32 rows=585234 width=0) (actual time=342.353..342.353 rows=579094 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-03-01'::date) AND (o_orderdate < '1993-06-01'::date))
                                                   Buffers: shared hit=103 read=1555
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..691921.34 rows=14971568 width=12) (actual time=0.122..15415.865 rows=14807952 loops=1)
                                       Buffers: shared hit=1003603 read=160220 dirtied=112 written=6663
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2639.546..2639.546 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=3 read=35275
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.043..1317.547 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.030..0.030 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=0.009..0.015 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 31684.851 ms
(40 rows)

COMMIT;
COMMIT