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 '1994-08-01'
	and o_orderdate < cast(date '1994-08-01' + 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=1195709.80..1195709.85 rows=20 width=176) (actual time=27369.823..27369.831 rows=20 loops=1)
   Buffers: shared hit=737540 read=690495 dirtied=2616 written=42
   ->  Sort  (cost=1195709.80..1197136.28 rows=570592 width=176) (actual time=27369.818..27369.822 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=737540 read=690495 dirtied=2616 written=42
         ->  HashAggregate  (cost=1174820.63..1180526.55 rows=570592 width=176) (actual time=26833.051..27211.417 rows=381555 loops=1)
               Buffers: shared hit=737537 read=690495 dirtied=2616 written=42
               ->  Hash Join  (cost=401365.97..1160555.83 rows=570592 width=176) (actual time=4961.155..24338.538 rows=1146697 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=737537 read=690495 dirtied=2616 written=42
                     ->  Hash Join  (cost=401364.41..1152708.63 rows=570592 width=154) (actual time=4961.110..23854.893 rows=1146697 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=737536 read=690495 dirtied=2616 written=42
                           ->  Merge Join  (cost=332336.41..1072268.79 rows=570592 width=12) (actual time=2278.496..18991.443 rows=1146697 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=737533 read=655220 dirtied=2616 written=31
                                 ->  Sort  (cost=332336.39..333776.73 rows=576137 width=8) (actual time=2278.286..2417.129 rows=573799 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51473kB
                                       Buffers: shared hit=204184 read=28128 dirtied=260
                                       ->  Bitmap Heap Scan on orders  (cost=12515.39..277211.45 rows=576137 width=8) (actual time=312.647..2074.263 rows=573799 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                             Buffers: shared hit=204184 read=28128 dirtied=260
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12371.36 rows=576137 width=0) (actual time=229.543..229.543 rows=579508 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                                   Buffers: shared read=1661
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..693798.32 rows=15018995 width=12) (actual time=0.131..14243.639 rows=14822651 loops=1)
                                       Buffers: shared hit=533349 read=627092 dirtied=2356 written=31
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2680.624..2680.624 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=3 read=35275 written=11
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.010..1051.154 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275 written=11
                     ->  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=0.008..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 27444.817 ms
(40 rows)

COMMIT;
COMMIT