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 '1993-07-01'
	and o_orderdate < cast(date '1993-07-01' + 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=1190779.31..1190779.36 rows=20 width=175) (actual time=54081.772..54081.781 rows=20 loops=1)
   Buffers: shared hit=595463 read=833135 written=13346
   ->  Sort  (cost=1190779.31..1192193.83 rows=565806 width=175) (actual time=54081.767..54081.772 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=595463 read=833135 written=13346
         ->  HashAggregate  (cost=1170065.36..1175723.42 rows=565806 width=175) (actual time=53373.088..53825.657 rows=381908 loops=1)
               Buffers: shared hit=595460 read=833135 written=13346
               ->  Hash Join  (cost=401725.39..1155920.21 rows=565806 width=175) (actual time=6738.209..49232.406 rows=1148355 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=595460 read=833135 written=13346
                     ->  Hash Join  (cost=401723.83..1148138.82 rows=565806 width=153) (actual time=6738.163..48366.881 rows=1148355 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=595459 read=833135 written=13346
                           ->  Merge Join  (cost=332695.83..1067794.70 rows=565806 width=12) (actual time=3843.297..42652.183 rows=1148355 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=560181 read=833135 written=13346
                                 ->  Sort  (cost=332695.81..334138.07 rows=576905 width=8) (actual time=3843.055..4051.438 rows=574350 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51499kB
                                       Buffers: shared hit=226523 read=5875
                                       ->  Bitmap Heap Scan on orders  (cost=12531.27..277491.84 rows=576905 width=8) (actual time=539.003..3011.140 rows=574350 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                             Buffers: shared hit=226523 read=5875
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12387.04 rows=576905 width=0) (actual time=410.217..410.217 rows=580443 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                                   Buffers: shared read=1661
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..689336.63 rows=14887870 width=12) (actual time=0.127..34911.646 rows=14822518 loops=1)
                                       Buffers: shared hit=333658 read=827260 written=13346
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2892.330..2892.330 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..1171.767 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.023..0.023 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..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 54187.490 ms
(40 rows)

COMMIT;
COMMIT