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=1149921.06..1149921.11 rows=20 width=175) (actual time=20675.531..20675.537 rows=20 loops=1)
   Buffers: shared hit=853714 read=568350 dirtied=866 written=152
   ->  Sort  (cost=1149921.06..1151324.43 rows=561347 width=175) (actual time=20675.527..20675.530 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=853714 read=568350 dirtied=866 written=152
         ->  HashAggregate  (cost=1129370.35..1134983.82 rows=561347 width=175) (actual time=20294.133..20542.797 rows=374839 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=853711 read=568350 dirtied=866 written=152
               ->  Hash Join  (cost=351327.18..1115336.67 rows=561347 width=175) (actual time=3991.891..17407.323 rows=1120427 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=853711 read=568350 dirtied=866 written=152
                     ->  Hash Join  (cost=351325.62..1107616.59 rows=561347 width=153) (actual time=3991.829..17049.557 rows=1120427 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=853710 read=568350 dirtied=866 written=152
                           ->  Hash Join  (cost=282297.62..1030168.38 rows=561347 width=12) (actual time=2560.555..14984.828 rows=1120427 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=819740 read=567042 dirtied=866 written=150
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686598.50 rows=14842461 width=12) (actual time=0.066..9432.405 rows=14808721 loops=1)
                                       Buffers: shared hit=759523 read=397889 dirtied=866 written=61
                                 ->  Hash  (cost=275170.44..275170.44 rows=570139 width=8) (actual time=2555.274..2555.274 rows=560081 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30071kB
                                       Buffers: shared hit=60217 read=169153 written=89
                                       ->  Bitmap Heap Scan on orders  (cost=12084.36..275170.44 rows=570139 width=8) (actual time=233.730..2370.317 rows=560081 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Heap Blocks: exact=227834
                                             Buffers: shared hit=60217 read=169153 written=89
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11941.82 rows=570139 width=0) (actual time=158.725..158.725 rows=562958 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared read=1536
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1420.555..1420.555 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=33970 read=1308 written=2
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.014..593.793 rows=1500000 loops=1)
                                       Buffers: shared hit=33970 read=1308 written=2
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.045..0.045 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=0.013..0.020 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.528 ms
 Execution time: 20698.376 ms
(42 rows)

COMMIT;
COMMIT