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=1153935.68..1153935.73 rows=20 width=175) (actual time=25887.481..25887.489 rows=20 loops=1)
   Buffers: shared hit=1007760 read=417257 dirtied=967 written=638
   ->  Sort  (cost=1153935.68..1155319.17 rows=553395 width=175) (actual time=25887.478..25887.482 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=1007760 read=417257 dirtied=967 written=638
         ->  HashAggregate  (cost=1133676.09..1139210.04 rows=553395 width=175) (actual time=25531.459..25745.315 rows=375156 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=1007757 read=417257 dirtied=967 written=638
               ->  Hash Join  (cost=352192.07..1119841.22 rows=553395 width=175) (actual time=5854.557..23535.771 rows=1121571 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1007757 read=417257 dirtied=967 written=638
                     ->  Hash Join  (cost=352190.51..1112230.47 rows=553395 width=153) (actual time=5854.504..23132.991 rows=1121571 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1007756 read=417257 dirtied=967 written=638
                           ->  Hash Join  (cost=283162.51..1034901.55 rows=553395 width=12) (actual time=3105.769..19611.160 rows=1121571 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=1007754 read=381981 dirtied=967 written=523
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..690229.04 rows=14927063 width=12) (actual time=0.111..12933.315 rows=14822845 loops=1)
                                       Buffers: shared hit=851617 read=307758 dirtied=791 written=431
                                 ->  Hash  (cost=276148.29..276148.29 rows=561103 width=8) (actual time=3096.784..3096.784 rows=560715 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30095kB
                                       Buffers: shared hit=156137 read=74223 dirtied=176 written=92
                                       ->  Bitmap Heap Scan on orders  (cost=12183.74..276148.29 rows=561103 width=8) (actual time=445.398..2882.909 rows=560715 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Heap Blocks: exact=228742
                                             Buffers: shared hit=156137 read=74223 dirtied=176 written=92
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12043.46 rows=561103 width=0) (actual time=317.627..317.627 rows=565209 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared read=1618 written=1
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2731.005..2731.005 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276 written=115
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.023..1452.758 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276 written=115
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.031..0.031 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..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.780 ms
 Execution time: 25911.069 ms
(42 rows)

COMMIT;
COMMIT