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 '1994-07-01'
	and o_orderdate < cast(date '1994-07-01' + 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=1193627.15..1193627.20 rows=20 width=176) (actual time=31866.155..31866.161 rows=20 loops=1)
   Buffers: shared hit=1351068 read=76420 dirtied=1479 written=2166
   ->  Sort  (cost=1193627.15..1195058.37 rows=572488 width=176) (actual time=31866.150..31866.154 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=1351068 read=76420 dirtied=1479 written=2166
         ->  HashAggregate  (cost=1172668.57..1178393.45 rows=572488 width=176) (actual time=31233.550..31649.741 rows=381475 loops=1)
               Buffers: shared hit=1351065 read=76420 dirtied=1479 written=2166
               ->  Hash Join  (cost=401641.67..1158356.37 rows=572488 width=176) (actual time=5584.676..27384.291 rows=1147013 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1351065 read=76420 dirtied=1479 written=2166
                     ->  Hash Join  (cost=401640.11..1150483.10 rows=572488 width=154) (actual time=5584.622..26698.636 rows=1147013 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1351064 read=76420 dirtied=1479 written=2166
                           ->  Merge Join  (cost=332612.11..1070005.34 rows=572488 width=12) (actual time=3036.776..21621.069 rows=1147013 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1325968 read=66238 dirtied=1479 written=2166
                                 ->  Sort  (cost=332612.09..334061.96 rows=579950 width=8) (actual time=3036.601..3218.819 rows=573917 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51479kB
                                       Buffers: shared hit=220046 read=12220 dirtied=233
                                       ->  Bitmap Heap Scan on orders  (cost=12594.47..277094.72 rows=579950 width=8) (actual time=673.876..2770.186 rows=573917 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                             Buffers: shared hit=220046 read=12220 dirtied=233
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12449.49 rows=579950 width=0) (actual time=465.220..465.220 rows=579094 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                                   Buffers: shared read=1662
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..691381.03 rows=14955036 width=12) (actual time=0.150..15141.187 rows=14822772 loops=1)
                                       Buffers: shared hit=1105922 read=54018 dirtied=1246 written=2166
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2545.451..2545.451 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=25096 read=10182
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.018..1179.497 rows=1500000 loops=1)
                                       Buffers: shared hit=25096 read=10182
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.029..0.029 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=0.010..0.017 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 31938.109 ms
(40 rows)

COMMIT;
COMMIT