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 '1994-04-01'
	and o_orderdate < cast(date '1994-04-01' + 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=1153676.62..1153676.67 rows=20 width=175) (actual time=23254.275..23254.283 rows=20 loops=1)
   Buffers: shared hit=1298360 read=119705 written=5277
   ->  Sort  (cost=1153676.62..1155062.22 rows=554239 width=175) (actual time=23254.272..23254.277 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=1298360 read=119705 written=5277
         ->  HashAggregate  (cost=1133386.13..1138928.52 rows=554239 width=175) (actual time=22801.264..23109.447 rows=378759 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=1298357 read=119705 written=5277
               ->  Hash Join  (cost=352251.07..1119530.15 rows=554239 width=175) (actual time=4670.035..20405.513 rows=1136916 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1298357 read=119705 written=5277
                     ->  Hash Join  (cost=352249.51..1111907.80 rows=554239 width=153) (actual time=4669.995..20026.001 rows=1136916 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1298356 read=119705 written=5277
                           ->  Hash Join  (cost=283221.51..1034566.22 rows=554239 width=12) (actual time=2745.036..16994.181 rows=1136916 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=1298353 read=84430 written=5277
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..689865.05 rows=14916721 width=12) (actual time=0.062..9090.445 rows=14807964 loops=1)
                                       Buffers: shared hit=1070819 read=80808 written=5277
                                 ->  Hash  (cost=276191.72..276191.72 rows=562348 width=8) (actual time=1703.667..1703.667 rows=568048 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30382kB
                                       Buffers: shared hit=227534 read=3622
                                       ->  Bitmap Heap Scan on orders  (cost=12208.50..276191.72 rows=562348 width=8) (actual time=275.092..1525.643 rows=568048 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Heap Blocks: exact=229520
                                             Buffers: shared hit=227534 read=3622
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12067.91 rows=562348 width=0) (actual time=196.948..196.948 rows=573228 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared hit=1 read=1635
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1911.285..1911.285 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=3 read=35275
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.016..914.794 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275
                     ->  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: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.008..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.399 ms
 Execution time: 23275.808 ms
(42 rows)

COMMIT;
COMMIT