dblink 哪种效果性能好

1.
A库
create view t1 as
select 'a' from dual
union
select 'b' from dual
B库通过dblink访问视图select * from t1@dblink

2.
B库
create view t1 as
select 'a' from dual@dblink
union
select 'b' from dual@dblink

B库访问视图 select * from t1
两种效果哪个好呢？

za