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 '1994-08-01'
	and o_orderdate < cast(date '1994-08-01' + 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=1202017.23..1202017.28 rows=20 width=175) (actual time=97904.573..97904.579 rows=20 loops=1)
   Buffers: shared hit=646253 read=788487 dirtied=227 written=987
   ->  Sort  (cost=1202017.23..1203463.60 rows=578550 width=175) (actual time=97904.569..97904.570 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=646253 read=788487 dirtied=227 written=987
         ->  HashAggregate  (cost=1180836.72..1186622.22 rows=578550 width=175) (actual time=97326.152..97680.191 rows=381537 loops=1)
               Buffers: shared hit=646250 read=788487 dirtied=227 written=987
               ->  Hash Join  (cost=403429.42..1166372.97 rows=578550 width=175) (actual time=6770.521..92226.232 rows=1146526 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=646250 read=788487 dirtied=227 written=987
                     ->  Hash Join  (cost=403427.85..1158416.34 rows=578550 width=153) (actual time=6770.469..91220.727 rows=1146526 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=646249 read=788487 dirtied=227 written=987
                           ->  Merge Join  (cost=334399.85..1077817.34 rows=578550 width=12) (actual time=4126.622..85814.332 rows=1146526 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=610971 read=788487 dirtied=227 written=987
                                 ->  Sort  (cost=334399.85..335859.06 rows=583684 width=8) (actual time=4124.287..4366.408 rows=573737 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51470kB
                                       Buffers: shared hit=222541 read=10661 dirtied=227 written=548
                                       ->  Bitmap Heap Scan on orders  (cost=12676.76..278498.02 rows=583684 width=8) (actual time=341.234..3827.851 rows=573737 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                             Buffers: shared hit=222541 read=10661 dirtied=227 written=548
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12530.84 rows=583684 width=0) (actual time=255.238..255.238 rows=581723 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-08-01'::date) AND (o_orderdate < '1994-11-01'::date))
                                                   Buffers: shared hit=100 read=1564 written=157
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..696987.86 rows=15090968 width=12) (actual time=0.825..77489.496 rows=14822310 loops=1)
                                       Buffers: shared hit=388430 read=777826 written=439
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2641.807..2641.807 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=0.016..1469.245 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  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=0.010..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 97955.332 ms
(40 rows)

COMMIT;
COMMIT