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 '1993-02-01'
	and o_orderdate < cast(date '1993-02-01' + 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=1187687.62..1187687.67 rows=20 width=176) (actual time=31719.241..31719.247 rows=20 loops=1)
   Buffers: shared hit=1064942 read=358185 dirtied=1244 written=720
   ->  Sort  (cost=1187687.62..1189089.90 rows=560914 width=176) (actual time=31719.237..31719.240 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=1064942 read=358185 dirtied=1244 written=720
         ->  HashAggregate  (cost=1167152.76..1172761.90 rows=560914 width=176) (actual time=31027.346..31471.746 rows=372963 loops=1)
               Buffers: shared hit=1064939 read=358185 dirtied=1244 written=720
               ->  Hash Join  (cost=399142.94..1153129.91 rows=560914 width=176) (actual time=4387.790..27854.834 rows=1113978 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1064939 read=358185 dirtied=1244 written=720
                     ->  Hash Join  (cost=399141.38..1145415.78 rows=560914 width=154) (actual time=4387.733..27220.052 rows=1113978 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1064938 read=358185 dirtied=1244 written=720
                           ->  Merge Join  (cost=330113.38..1065169.50 rows=560914 width=12) (actual time=2540.617..22810.818 rows=1113978 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1029660 read=358185 dirtied=1244 written=720
                                 ->  Sort  (cost=330113.36..331533.91 rows=568221 width=8) (actual time=2540.448..2710.773 rows=555734 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50627kB
                                       Buffers: shared hit=224777 read=4645 dirtied=223
                                       ->  Bitmap Heap Scan on orders  (cost=12238.22..275802.53 rows=568221 width=8) (actual time=436.556..2224.412 rows=555734 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-02-01'::date) AND (o_orderdate < '1993-05-01'::date))
                                             Buffers: shared hit=224777 read=4645 dirtied=223
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12096.16 rows=568221 width=0) (actual time=310.547..310.547 rows=558991 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-02-01'::date) AND (o_orderdate < '1993-05-01'::date))
                                                   Buffers: shared hit=105 read=1474
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..689329.14 rows=14910700 width=12) (actual time=0.104..17031.206 rows=14822925 loops=1)
                                       Buffers: shared hit=804883 read=353540 dirtied=1021 written=720
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1845.141..1845.141 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=146) (actual time=0.016..716.394 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.027..0.027 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=0.011..0.017 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 31807.408 ms
(40 rows)

COMMIT;
COMMIT