今天突然有客户问我一个问题，数据库要添加一个监控用户，想做一个会话数的限制，这里做了一个小测试，平日维护的时候也需要关注一下数据库的资源限制。
<roidb1:orcl1:/home/oracle>$sqlplus / as sysdba
sql*Plus: Release 11.2.0.4.0 Production on Mon Sep 18 18:16:19 2017
copyright (c) 1982,2013,Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning,Real Application Clusters,Automatic Storage Management,OLAP,
Data Mining and Real Application Testing options
sql> show parameter resource_limit
NAME TYPE VALUE
------------------------------------ ----------- ---------
resource_limit boolean FALSE --默认值
sql>
sql> set linesize 160
sql> select * from dba_profiles order by 1,3,2;
PROFILE RESOURCE_NAME RESOURCE LIMIT
------------------------- -------------------------------- ------------ ---------
DEFAULT COMPOSITE_LIMIT KERNEL UNLIMITED
DEFAULT CONNECT_TIME KERNEL UNLIMITED
DEFAULT cpu_PER_CALL KERNEL UNLIMITED
DEFAULT cpu_PER_SESSION KERNEL UNLIMITED
DEFAULT IDLE_TIME KERNEL UNLIMITED
DEFAULT LOGICAL_READS_PER_CALL KERNEL UNLIMITED
DEFAULT LOGICAL_READS_PER_SESSION KERNEL UNLIMITED
DEFAULT PRIVATE_SGA KERNEL UNLIMITED
DEFAULT SESSIONS_PER_USER KERNEL UNLIMITED
DEFAULT Failed_LOGIN_ATTEMPTS PASSWORD 10
DEFAULT PASSWORD_GRACE_TIME PASSWORD 7
PROFILE RESOURCE_NAME RESOURCE LIMIT
------------------------- -------------------------------- ------------ --------
DEFAULT PASSWORD_LIFE_TIME PASSWORD 180
DEFAULT PASSWORD_LOCK_TIME PASSWORD 1
DEFAULT PASSWORD_REUSE_MAX PASSWORD UNLIMITED
DEFAULT PASSWORD_REUSE_TIME PASSWORD UNLIMITED
DEFAULT PASSWORD_VERIFY_FUNCTION PASSWORD NULL
MONITORING_PROFILE COMPOSITE_LIMIT KERNEL DEFAULT
MONITORING_PROFILE CONNECT_TIME KERNEL DEFAULT
MONITORING_PROFILE cpu_PER_CALL KERNEL DEFAULT
MONITORING_PROFILE cpu_PER_SESSION KERNEL DEFAULT
MONITORING_PROFILE IDLE_TIME KERNEL DEFAULT
MONITORING_PROFILE LOGICAL_READS_PER_CALL KERNEL DEFAULT
PROFILE RESOURCE_NAME RESOURCE LIMIT
------------------------- -------------------------------- ------------ ---------------
MONITORING_PROFILE LOGICAL_READS_PER_SESSION KERNEL DEFAULT
MONITORING_PROFILE PRIVATE_SGA KERNEL DEFAULT
MONITORING_PROFILE SESSIONS_PER_USER KERNEL DEFAULT
MONITORING_PROFILE Failed_LOGIN_ATTEMPTS PASSWORD UNLIMITED
MONITORING_PROFILE PASSWORD_GRACE_TIME PASSWORD DEFAULT
MONITORING_PROFILE PASSWORD_LIFE_TIME PASSWORD DEFAULT
MONITORING_PROFILE PASSWORD_LOCK_TIME PASSWORD DEFAULT
MONITORING_PROFILE PASSWORD_REUSE_MAX PASSWORD DEFAULT
MONITORING_PROFILE PASSWORD_REUSE_TIME PASSWORD DEFAULT
MONITORING_PROFILE PASSWORD_VERIFY_FUNCTION PASSWORD DEFAULT
32 rows selected.
测试1： Failed_LOGIN_ATTEMPTS=10 是否是生效
sql> create user roidba identified by roidba;
User created.
sql> grant connect,resource,dba to roidba;
Grant succeeded.
sql> exit
省略..................经过十次登陆...........
<roidb1:orcl1:/home/oracle>$sqlplus roidba/roidbaa
sql*Plus: Release 11.2.0.4.0 Production on Mon Sep 18 18:26:37 2017
copyright (c) 1982,Oracle. All rights reserved.
ERROR:
ORA-28000: the account is locked
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
Enter user-name:
实验证明不管 resource_limit 是否为true，和密码相关的限制都是生效，其他和密码相关的大家可以自己测试。
DEFAULT Failed_LOGIN_ATTEMPTS PASSWORD 10 --密码输入十次都是错误，用户锁定
DEFAULT PASSWORD_LOCK_TIME PASSWORD 1 --锁定一天以后自动解锁
DEFAULT PASSWORD_LIFE_TIME PASSWORD 180 --密码生命周期180天，之后密码失效
DEFAULT PASSWORD_GRACE_TIME PASSWORD 7 --宽限延续期，宽限期内登陆会有提示。
安装完数据库，一般会把password_life_time设置为unlimited。
sql> alter profile default limit password_life_time unlimited;
Profile altered.
继续测试2：
sql> create profile sess limit
2 SESSIONS_PER_USER 2;
Profile created.
sql> alter user roidba profile sess;
User altered.
sql> alter system set resource_limit=true;
System altered.
打开三个窗口，前两个都顺利登陆，第三个出现以下报错。
<roidb1:orcl1:/home/oracle>$sqlplus roidba/roidba
sql*Plus: Release 11.2.0.4.0 Production on Mon Sep 18 18:48:24 2017
copyright (c) 1982,Oracle. All rights reserved.
ERROR:
ORA-02391: exceeded simultaneous SESSIONS_PER_USER limit
Enter user-name:
小伙伴们，不要光看不练，花个十分二十分钟动手操作一下哈！
