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=1183541.33..1183541.38 rows=20 width=175) (actual time=34628.381..34628.387 rows=20 loops=1)
   Buffers: shared hit=515933 read=896931 dirtied=850 written=27272
   ->  Sort  (cost=1183541.33..1184935.46 rows=557654 width=175) (actual time=34628.377..34628.381 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=515933 read=896931 dirtied=850 written=27272
         ->  HashAggregate  (cost=1163125.82..1168702.36 rows=557654 width=175) (actual time=34112.498..34471.675 rows=375167 loops=1)
               Buffers: shared hit=515930 read=896931 dirtied=850 written=27272
               ->  Hash Join  (cost=397347.46..1149184.47 rows=557654 width=175) (actual time=7295.774..30625.907 rows=1121684 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=515930 read=896931 dirtied=850 written=27272
                     ->  Hash Join  (cost=397345.90..1141515.16 rows=557654 width=153) (actual time=7295.730..30087.778 rows=1121684 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=515929 read=896931 dirtied=850 written=27272
                           ->  Merge Join  (cost=328317.90..1061334.08 rows=557654 width=12) (actual time=3118.024..23331.100 rows=1121684 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=515927 read=861655 dirtied=850 written=27272
                                 ->  Sort  (cost=328317.86..329727.90 rows=564015 width=8) (actual time=3117.842..3270.398 rows=560661 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50857kB
                                       Buffers: shared hit=156437 read=72479
                                       ->  Bitmap Heap Scan on orders  (cost=11951.05..274439.27 rows=564015 width=8) (actual time=502.628..2849.716 rows=560661 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Buffers: shared hit=156437 read=72479
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11810.05 rows=564015 width=0) (actual time=357.136..357.136 rows=561844 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared hit=2 read=1532
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..687433.00 rows=14875264 width=12) (actual time=0.131..17493.749 rows=14823172 loops=1)
                                       Buffers: shared hit=359490 read=789176 dirtied=850 written=27272
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=4175.557..4175.557 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.005..1008.676 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.026..0.026 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..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 34722.417 ms
(40 rows)

COMMIT;
COMMIT