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=1194322.14..1194322.19 rows=20 width=175) (actual time=73257.778..73257.786 rows=20 loops=1)
   Buffers: shared hit=1194059 read=236793 dirtied=1862 written=5018
   ->  Sort  (cost=1194322.14..1195727.14 rows=562000 width=175) (actual time=73257.774..73257.778 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=1194059 read=236793 dirtied=1862 written=5018
         ->  HashAggregate  (cost=1173747.52..1179367.52 rows=562000 width=175) (actual time=72695.523..73081.607 rows=374863 loops=1)
               Buffers: shared hit=1194056 read=236793 dirtied=1862 written=5018
               ->  Hash Join  (cost=400045.51..1159697.52 rows=562000 width=175) (actual time=15933.635..68717.452 rows=1120391 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1194056 read=236793 dirtied=1862 written=5018
                     ->  Hash Join  (cost=400043.95..1151968.46 rows=562000 width=153) (actual time=15933.573..67770.986 rows=1120391 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1194055 read=236793 dirtied=1862 written=5018
                           ->  Merge Join  (cost=331015.95..1071700.46 rows=562000 width=12) (actual time=12837.314..62089.386 rows=1120391 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1158782 read=236788 dirtied=1862 written=5018
                                 ->  Sort  (cost=331015.94..332432.62 rows=566671 width=8) (actual time=12836.796..13049.543 rows=560109 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50832kB
                                       Buffers: shared hit=160879 read=69940 written=3952
                                       ->  Bitmap Heap Scan on orders  (cost=12310.37..276864.43 rows=566671 width=8) (actual time=730.387..12496.606 rows=560109 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Buffers: shared hit=160879 read=69940 written=3952
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12168.70 rows=566671 width=0) (actual time=608.409..608.409 rows=566327 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared read=1622 written=102
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694633.00 rows=15039948 width=12) (actual time=0.473..45245.257 rows=14807772 loops=1)
                                       Buffers: shared hit=997903 read=166848 dirtied=1862 written=1066
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3094.137..3094.137 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35273 read=5
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.018..1767.109 rows=1500000 loops=1)
                                       Buffers: shared hit=35273 read=5
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.033..0.033 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=0.009..0.016 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 73316.818 ms
(40 rows)

COMMIT;
COMMIT