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=1195129.26..1195129.31 rows=20 width=175) (actual time=65984.930..65984.938 rows=20 loops=1)
   Buffers: shared hit=1206978 read=219706 dirtied=10 written=7
   ->  Sort  (cost=1195129.26..1196545.94 rows=566674 width=175) (actual time=65984.925..65984.930 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=1206978 read=219706 dirtied=10 written=7
         ->  HashAggregate  (cost=1174383.52..1180050.26 rows=566674 width=175) (actual time=65461.883..65807.171 rows=371266 loops=1)
               Buffers: shared hit=1206975 read=219706 dirtied=10 written=7
               ->  Hash Join  (cost=400746.14..1160216.67 rows=566674 width=175) (actual time=10748.392..61791.527 rows=1079939 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1206975 read=219706 dirtied=10 written=7
                     ->  Hash Join  (cost=400744.58..1152423.34 rows=566674 width=153) (actual time=10748.336..60949.369 rows=1079939 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1206974 read=219706 dirtied=10 written=7
                           ->  Merge Join  (cost=331716.58..1072061.86 rows=566674 width=12) (actual time=7412.478..55146.312 rows=1079939 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1178056 read=213346 dirtied=10 written=7
                                 ->  Sort  (cost=331716.58..333145.84 rows=571705 width=8) (actual time=7412.013..7611.427 rows=561746 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50908kB
                                       Buffers: shared hit=223675 read=7286 written=4
                                       ->  Bitmap Heap Scan on orders  (cost=12417.96..277047.54 rows=571705 width=8) (actual time=648.056..7109.948 rows=561746 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Buffers: shared hit=223675 read=7286 written=4
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12275.04 rows=571705 width=0) (actual time=545.898..545.898 rows=567427 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                                   Buffers: shared read=1626
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694243.00 rows=15031491 width=12) (actual time=0.110..43887.531 rows=14822649 loops=1)
                                       Buffers: shared hit=954381 read=206060 dirtied=10 written=3
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3333.572..3333.572 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=28918 read=6360
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.022..1904.457 rows=1500000 loops=1)
                                       Buffers: shared hit=28918 read=6360
                     ->  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..0.019 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 66031.350 ms
(40 rows)

COMMIT;
COMMIT