Shulou(Shulou.com)06/01 Report--

In Oracle 11g, in order to improve security, Oracle introduced a new feature of "password delayed authentication". The effect of this feature is that if the user enters the wrong password to try to log in, as the number of login errors increases, so does the authentication time before each login, thus mitigating password attempt attacks that may be repeated against the database.

However, for a normal system, due to the change of password, there may be some missing clients that try again and again, resulting in a long wait for Library Cache Lock in the database, which is very common.

If you encounter this type of problem, you can eliminate this effect by turning off this feature through Event 28401. The following command sets the modification in the parameter file:

ALTER SYSTEM SET EVENT = '28401 TRACE NAME CONTEXT FOREVER, LEVEL 1' SCOPE = SPFILE

A very typical AWR report with such problems is as follows. First of all, in TOP 5, you may see significant Library Cache Lock waiting. The following example comes from the real situation in version 11.2.0.3.0:

In such cases, the following metrics are displayed in the time model-Time Model, where connection management call elapsed time occupies the main DB Time, and this wait directly indicates that it occurs when a database connection is established:

Such problems are common and identified in 11g of Oracle, and the corresponding records can be found on MOS:

High 'library cache lock' Wait Time Due to Invalid Login Attempts (1309738.1)

In addition, Oracle 11g enables password case verification. If you upgrade from Oracle 10g, you need to pay special attention to this change. You can control this feature by initializing the parameter SEC_CASE_SENSITIVE_LOGON.

The above is for reference.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.