分类： Oracle
2015-05-22 20:42:30
原文地址：11G延迟密码验证的取消 作者：tomsyan
11G引入了延迟密码验证，在输入错误的密码后，后续如果还是采用错误的密码登陆，将会导致密码延迟验证，
而且会导致失败登陆延长。如下：
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m0.160s
user 0m0.003s
sys 0m0.066s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m0.175s
user 0m0.003s
sys 0m0.065s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m0.185s
user 0m0.013s
sys 0m0.060s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m1.306s
user 0m0.040s
sys 0m0.088s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m2.176s
user 0m0.006s
sys 0m0.073s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m3.187s
user 0m0.003s
sys 0m0.074s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m4.162s
user 0m0.003s
sys 0m0.054s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m5.302s
user 0m0.004s
sys 0m0.077s
[oracle@db2server ~]$ time echo "select sysdate from dual;" | sqlplus -s scott/tige 1> /dev/null 2>&1
real 0m6.602s
user 0m0.007s
sys 0m0.075s
可以看到从第三次开始，后续的每次登陆导致密码延迟1秒左右。
如果有多个会话同时登陆，将会导致会话HANG住，出现一些LATCH的竞争。
可以通过如下事件来屏蔽密码的延迟验证。
ALTER SYSTEM SET EVENT = '28401 TRACE NAME CONTEXT FOREVER, LEVEL 1' SCOPE = SPFILE
[oracle@db2server ~]$ oerr ora 28401
28401, 00000, "Event to disable delay after three failed login attempts"
// *Document: NO
// *Cause: N/A
// *Action: Set this event in your environment to disable the login delay
// which will otherwise take place after three failed login attempts.
// *Note: THIS IS NOT A USER ERROR NUMBER/MESSAGE. THIS DOES NOT NEED TO BE
// TRANSLATED OR DOCUMENTED.
