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 '1994-09-01'
	and o_orderdate < cast(date '1994-09-01' + 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=1190908.00..1190908.05 rows=20 width=175) (actual time=86450.395..86450.404 rows=20 loops=1)
   Buffers: shared hit=994397 read=433130 written=12351
   ->  Sort  (cost=1190908.00..1192302.24 rows=557696 width=175) (actual time=86450.390..86450.396 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=994397 read=433130 written=12351
         ->  HashAggregate  (cost=1170490.95..1176067.91 rows=557696 width=175) (actual time=85886.501..86283.297 rows=378535 loops=1)
               Buffers: shared hit=994394 read=433130 written=12351
               ->  Hash Join  (cost=398973.46..1156548.55 rows=557696 width=175) (actual time=11937.853..81778.479 rows=1135845 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=994394 read=433130 written=12351
                     ->  Hash Join  (cost=398971.90..1148878.67 rows=557696 width=153) (actual time=11937.439..80815.186 rows=1135845 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=994393 read=433130 written=12351
                           ->  Merge Join  (cost=329943.90..1068696.75 rows=557696 width=12) (actual time=8666.909..74799.152 rows=1135845 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=959115 read=433130 written=12351
                                 ->  Sort  (cost=329943.90..331350.53 rows=562655 width=8) (actual time=8666.610..8893.806 rows=567796 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51192kB
                                       Buffers: shared hit=228584 read=2905
                                       ->  Bitmap Heap Scan on orders  (cost=12217.20..276205.02 rows=562655 width=8) (actual time=719.123..8348.163 rows=567796 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                             Buffers: shared hit=228584 read=2905
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12076.53 rows=562655 width=0) (actual time=589.190..589.190 rows=572910 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                                   Buffers: shared read=1641
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692860.39 rows=15001571 width=12) (actual time=0.180..62080.514 rows=14807964 loops=1)
                                       Buffers: shared hit=730531 read=430225 written=12351
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3268.405..3268.405 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.019..1914.537 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.387..0.387 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=0.362..0.370 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 86509.739 ms
(40 rows)

COMMIT;
COMMIT