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 '1994-03-01'
	and o_orderdate < cast(date '1994-03-01' + 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=1184548.96..1184549.01 rows=20 width=175) (actual time=32100.590..32100.599 rows=20 loops=1)
   Buffers: shared hit=981192 read=428141 dirtied=114 written=6373
   ->  Sort  (cost=1184548.96..1185972.42 rows=569382 width=175) (actual time=32100.584..32100.590 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=981192 read=428141 dirtied=114 written=6373
         ->  HashAggregate  (cost=1163704.09..1169397.91 rows=569382 width=175) (actual time=31515.362..31939.570 rows=381126 loops=1)
               Buffers: shared hit=981189 read=428141 dirtied=114 written=6373
               ->  Hash Join  (cost=398504.96..1149469.54 rows=569382 width=175) (actual time=8728.578..27563.403 rows=1147436 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=981189 read=428141 dirtied=114 written=6373
                     ->  Hash Join  (cost=398503.40..1141638.98 rows=569382 width=153) (actual time=8728.538..26992.371 rows=1147436 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=981188 read=428141 dirtied=114 written=6373
                           ->  Merge Join  (cost=329475.40..1061223.34 rows=569382 width=12) (actual time=5102.604..20872.019 rows=1147436 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=946445 read=427606 dirtied=114 written=6373
                                 ->  Sort  (cost=329475.36..330915.06 rows=575880 width=8) (actual time=5102.421..5254.317 rows=573069 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51439kB
                                       Buffers: shared hit=27820 read=202087
                                       ->  Bitmap Heap Scan on orders  (cost=12216.67..274376.87 rows=575880 width=8) (actual time=341.874..4826.810 rows=573069 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Buffers: shared hit=27820 read=202087
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12072.70 rows=575880 width=0) (actual time=259.794..259.794 rows=573681 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared hit=1569 read=1
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..686062.39 rows=14845572 width=12) (actual time=0.137..12940.254 rows=14808303 loops=1)
                                       Buffers: shared hit=918625 read=225519 dirtied=114 written=6373
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3623.952..3623.952 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=34743 read=535
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.014..733.176 rows=1500000 loops=1)
                                       Buffers: shared hit=34743 read=535
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.019..0.019 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..0.008 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 32185.415 ms
(40 rows)

COMMIT;
COMMIT