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 '1995-01-01'
	and o_orderdate < cast(date '1995-01-01' + 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=1181164.81..1181164.86 rows=20 width=176) (actual time=53230.912..53230.920 rows=20 loops=1)
   Buffers: shared hit=715773 read=694235 dirtied=10 written=17857
   ->  Sort  (cost=1181164.81..1182549.35 rows=553817 width=176) (actual time=53230.909..53230.914 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=715773 read=694235 dirtied=10 written=17857
         ->  HashAggregate  (cost=1160889.77..1166427.94 rows=553817 width=176) (actual time=52473.184..52990.334 rows=354681 loops=1)
               Buffers: shared hit=715770 read=694235 dirtied=10 written=17857
               ->  Hash Join  (cost=396637.10..1147044.34 rows=553817 width=176) (actual time=7721.648..41764.164 rows=940961 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=715770 read=694235 dirtied=10 written=17857
                     ->  Hash Join  (cost=396635.54..1139427.80 rows=553817 width=154) (actual time=7721.599..41113.182 rows=940961 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=715769 read=694235 dirtied=10 written=17857
                           ->  Merge Join  (cost=327607.54..1059323.46 rows=553817 width=12) (actual time=4099.644..34611.243 rows=940961 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=715766 read=658960 dirtied=10 written=17857
                                 ->  Sort  (cost=327607.53..329009.18 rows=560660 width=8) (actual time=4099.337..4308.711 rows=561597 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50901kB
                                       Buffers: shared hit=221256 read=7629 dirtied=10
                                       ->  Bitmap Heap Scan on orders  (cost=11888.66..274073.56 rows=560660 width=8) (actual time=468.557..2309.053 rows=561597 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                             Buffers: shared hit=221256 read=7629 dirtied=10
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11748.50 rows=560660 width=0) (actual time=363.813..363.813 rows=562722 loops=1)
                                                   Index Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                                   Buffers: shared read=1538
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..686258.14 rows=14846529 width=12) (actual time=0.116..26906.814 rows=14808181 loops=1)
                                       Buffers: shared hit=494510 read=651331 written=17857
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=3620.168..3620.168 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=146) (actual time=0.016..1189.732 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.026..0.026 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..0.016 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 53355.098 ms
(40 rows)

COMMIT;
COMMIT