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 '1993-11-01'
	and o_orderdate < cast(date '1993-11-01' + 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=1191215.90..1191215.95 rows=20 width=175) (actual time=29108.365..29108.373 rows=20 loops=1)
   Buffers: shared hit=1273389 read=151680 dirtied=2803 written=687
   ->  Sort  (cost=1191215.90..1192646.86 rows=572382 width=175) (actual time=29108.362..29108.368 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=1273389 read=151680 dirtied=2803 written=687
         ->  HashAggregate  (cost=1170261.20..1175985.02 rows=572382 width=175) (actual time=28517.788..28928.401 rows=381592 loops=1)
               Buffers: shared hit=1273386 read=151680 dirtied=2803 written=687
               ->  Hash Join  (cost=400655.40..1155951.65 rows=572382 width=175) (actual time=4690.457..25460.468 rows=1148335 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1273386 read=151680 dirtied=2803 written=687
                     ->  Hash Join  (cost=400653.84..1148079.84 rows=572382 width=153) (actual time=4690.417..24840.325 rows=1148335 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1273385 read=151680 dirtied=2803 written=687
                           ->  Merge Join  (cost=331625.84..1067604.20 rows=572382 width=12) (actual time=2423.303..20155.427 rows=1148335 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1238107 read=151680 dirtied=2803 written=687
                                 ->  Sort  (cost=331625.84..333073.49 rows=579059 width=8) (actual time=2423.090..2601.834 rows=574176 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51491kB
                                       Buffers: shared hit=229834 read=1529 dirtied=453
                                       ->  Bitmap Heap Scan on orders  (cost=12473.31..276200.19 rows=579059 width=8) (actual time=299.933..2191.421 rows=574176 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-11-01'::date) AND (o_orderdate < '1994-02-01'::date))
                                             Buffers: shared hit=229834 read=1529 dirtied=453
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12328.54 rows=579059 width=0) (actual time=221.531..221.531 rows=577555 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-11-01'::date) AND (o_orderdate < '1994-02-01'::date))
                                                   Buffers: shared hit=103 read=1529
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..690034.49 rows=14930777 width=12) (actual time=0.183..14687.586 rows=14822937 loops=1)
                                       Buffers: shared hit=1008273 read=150151 dirtied=2350 written=687
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2265.195..2265.195 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=145) (actual time=0.011..962.207 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.021..0.021 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..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 29179.123 ms
(40 rows)

COMMIT;
COMMIT