Oracle中profile的作用？

create profile new_profile
limit password_reuse_max 10
password_reuse_time 30;

2．设置profile资源限制：
create profile app_user limit
sessions_per_user unlimited
cpu_per_session unlimited
cpu_per_call 3000
connect_time 45
logical_reads_per_session default
logical_reads_per_call 1000
private_sga 15k
composite_limit 5000000;
总的resource cost不超过五百万service units。计算总的resource cost的公式由alter resource cost语句来指定。

3．设置密码限制profile：
create profile app_users2 limit
failed_login_attempts 5
password_life_time 60
password_reuse_time 60
password_reuse_max 5
password_verify_function verify_function
password_lock_time