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 '1994-01-01'
	and o_orderdate < cast(date '1994-01-01' + 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=1189670.57..1189670.62 rows=20 width=175) (actual time=39272.041..39272.046 rows=20 loops=1)
   Buffers: shared hit=697328 read=728491 dirtied=235 written=212
   ->  Sort  (cost=1189670.57..1191056.07 rows=554202 width=175) (actual time=39272.035..39272.037 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=697328 read=728491 dirtied=235 written=212
         ->  HashAggregate  (cost=1169381.43..1174923.45 rows=554202 width=175) (actual time=38706.789..39095.013 rows=375161 loops=1)
               Buffers: shared hit=697325 read=728491 dirtied=235 written=212
               ->  Hash Join  (cost=398952.59..1155526.38 rows=554202 width=175) (actual time=6794.551..35041.234 rows=1121576 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=697325 read=728491 dirtied=235 written=212
                     ->  Hash Join  (cost=398951.02..1147904.54 rows=554202 width=153) (actual time=6794.504..34254.698 rows=1121576 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=697324 read=728491 dirtied=235 written=212
                           ->  Merge Join  (cost=329923.02..1067792.50 rows=554202 width=12) (actual time=3568.376..28608.146 rows=1121576 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=697322 read=693215 dirtied=235 written=212
                                 ->  Sort  (cost=329923.02..331324.70 rows=560671 width=8) (actual time=3568.164..3774.634 rows=560676 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50858kB
                                       Buffers: shared hit=183852 read=46747 dirtied=235
                                       ->  Bitmap Heap Scan on orders  (cost=12176.86..276387.93 rows=560671 width=8) (actual time=549.021..3270.710 rows=560676 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Buffers: shared hit=183852 read=46747 dirtied=235
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12036.70 rows=560671 width=0) (actual time=422.325..422.325 rows=565778 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared read=1621
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692088.41 rows=14975172 width=12) (actual time=0.154..21368.777 rows=14822752 loops=1)
                                       Buffers: shared hit=513470 read=646468 written=212
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3224.183..3224.183 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.007..1589.983 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.021..0.021 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..0.008 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 39314.816 ms
(40 rows)

COMMIT;
COMMIT