alter session set skip_unusable_indexes=false；

3，重建失效索引

alter index PK_CARD rebuild;

4，重新检查索引状态：

select index_name,index_type,tablespace_name,table_type,status from user_indexes where index_name='PK_CARD';

发现该索引状态变为VALID。

二、Active Session History (ASH) performed an emergency flush. This may mean that ASH is undersized. If emergency flushes are a recurring issue, you may consider increasing ASH size by setting the value of _ASH_SIZE to a sufficiently large value. Currently, ASH size is 25165824 bytes. Both ASH size and the total number of emergency flushes since instance startup can be monitored by running the following query:

 select total_size,awr_flush_emergency_count from v$ash_info;

解决方法：

1，SQL> select total_size,awr_flush_emergency_count from v$ash_info;

TOTAL_SIZE AWR_FLUSH_EMERGENCY_COUNT

---------- -------------------------

  25165824 4

2，SQL> select x.ksppinm name,y.ksppstvl value,y.ksppstdf isdefault,decode(bitand(y.ksppstvf,7),1,'MODIFIED',4,'SYSTEM_MOD','FALSE') ismod,decode(bitand(y.ksppstvf,2),2,'TRUE','FALSE') isadj from sys.x$ksppi x,sys.x$ksppcv y where x.inst_id = userenv('Instance') and y.inst_id = userenv('Instance') and x.indx = y.indx and x.ksppinm ='_ash_size' order by translate(x.ksppinm, ' _', ' ');

NAME

--------------------------------------------------------------------------------

VALUE

--------------------------------------------------------------------------------

ISDEFAULT ISMOD ISADJ

--------- ---------- -----

_ash_size

1048618

TRUE FALSE FALSE

3，增大_ash_size值

alter system set "_ash_size"=67108864;

三、FFatal NI connect error 12170.

  VERSION INFORMATION:

        TNS for Linux: Version 11.2.0.4.0 - Production

        Oracle Bequeath NT Protocol Adapter for Linux: Version 11.2.0.4.0 - Production

        TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.4.0 - Production

  Time: 20-6月 -2014 11:50:34

  Tracing not turned on.

  Tns error struct:

    ns main err code: 12535     

TNS-12535: TNS: 操作超时

    ns secondary err code: 12560

    nt main err code: 505     

TNS-00505: 操作超时

    nt secondary err code: 110

    nt OS err code: 0

  Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=192.168.4.202)(PORT=56142))

为什么会出现这样的情况呢？网上搜索后得知，在Oracle11G中，

 有这样两个参数SQLNET.INBOUND_CONNECT_TIMEOUT 和INBOUND_CONNECT_TIMEOUT_listenername；他们的默认值为60s，

 这两个参数负责登陆用户与服务器验证的超时时间，在10GR2以前的版本默认是0s，为了防止Denial of Service (DOS)攻击，

 在以后的版本中才设置为60s。如果在登录过程中，服务器没有给出及时的响应，那么将会在60后给出错误提示，

 这个超时时间显然有点过长，导致用户重复登陆的频率加大，频繁的登录引起数据库负载过大。

解决方法：

LSNRCTL> show inbound_connect_timeout

正在连接到 (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))

LISTENER 参数 "inbound_connect_timeout" 设为 60

命令执行成功

LSNRCTL> set inbound_connect_timeout 0

正在连接到 (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))

LISTENER 参数 "inbound_connect_timeout" 设为 0

命令执行成功

LSNRCTL> show inbound_connect_timeout

正在连接到 (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))

LISTENER 参数 "inbound_connect_timeout" 设为 0

命令执行成功

LSNRCTL> set save_config_on_stop on   #指定在一个lsnrctl会话期内所发生的修改在退出时是否应该被保存起来，下次监听启动也是生效的  on 保存 off 不保存

正在连接到 (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))

LISTENER 参数 "save_config_on_stop" 设为 ON

命令执行成功

LSNRCTL> exit