Automatic Oracle Instance Registration

A feature called automatic Oracle instance registration is the ability of an instance to register itself automatically with the listener at startup. Before Oracle 8i, an instance had to be configured via the listener.ora file. Now Oracle provides automated instance registration with the associated listener. Database instance registration enables load balancing and failover features as well.

When started, the database will register itself with the default listener without any additional configuration requirements. If you use multiple listener configurations, then you will need to add some additional parameters to the parameter file or spfile file for that instance. Configuration for listeners other than the default listener will require the inclusion of the SERVICE_NAME and LOCAL_LISTENER optional parameters in the init.ora file of the instance you want registered. Note that the LOCAL_LISTENER parameter also overrides other parameters of Shared server configuration. This is most important thing and as Oracle DBA you should need to aware of this.

If you use multiple listeners, you will need to modify your parameter file or you will find your database registering itself with both the listener you have defined for it and the default listener.

Can Oracle DBA Interview Questions help to clear Technical Interview?

How to Clear Tough Technical Interview Of Oracle DBA?

Different Oracle version has different kind of features. Every time Oracle changes version and introduces new features with new version. But company’s basic requirement is same. It cannot change with version changes. Due to this reason, interviewer thinks first company’s requirement and tries to ask those kinds of interview questions. Candidate should have superb knowledge of Oracle fundamentals and basic architecture. Candidate should need to keen about company’s basic requirement of opening.

We cannot say that interviewer would ask you same question from any book but interviewer always tries to test your skills and ask questions start from basics to advance. Real time scenario based Oracle DBA interview questions are very tough to understand and crack it. Those are based on practical hands on or experience. If you are able to understand those queries then easily crack it.

Sometimes interviewer tries to ask those questions, which are not related with their requirement. This time, interviewers attempt to read candidate’s mind about in toughest condition or situation how he or she would act. Take example, candidate acts normally any disaster recovery scenario. This kind of situation might not occur in company any time but they are asking this kind of questions to candidate.

Some good and nice book which contains only Oracle DBA Interview Questions Answers, then it would useful to candidate as well as interviewer too. Because using this kind of book, it becomes easier to judge candidate for all expectations without making prior home work. Interviewer always prefers this kind of book and use in any kind of interviews from junior level of interview to senior level of interview.

Every candidate fears about real time scenario based interview questions in technical interview of Oracle. They are not assuming which kind of questions is being asked. Due to this reason, they are losing self confidence before interview and finally they failed in technical interview. For avoiding this kind of situation, you need to prepare yourself using some nice quick ready reference book. Prepare with real time scenario based questions and think about another which kind of questions would be asked. Once you get basic idea and concept of this, you can easily judge another questions too. This situation would build your confidence.

Be careful about your preparation; take help of any good nice Oracle DBA Interview Questions book. Appear in your technical interview without hesitation, you would get success. Today, latest edition of Oracle DBA interview questions answers Book has been released with 4th edition. Discount rate is being offered for very limited time.

How to Get Success in Oracle Performance Tuning?

This topic has been discussing so many times in different blog and different books. Every Oracle DBA is interesting to get success in Oracle performance tuning. I have published so many articles on same topic. Still I am asked same query by so many Oracle DBAs. Those Oracle DBAs are very keen to get answer to solve this mystery.

Oracle performance tuning doesn’t like mystery. Performance slowness would start in your database server and slowly it would be impacting all active sessions. Performance bottleneck doesn’t occur immediately and reflect drastically. But it started from very beginning and increasing rapidly sometimes. If you are well experienced Oracle DBA then you can judge for future impacts of some incidents. These symptoms and characteristics can be judged using constant monitoring of databases. If you are constantly monitoring your databases, then you can able to mark some incidents like buffer cache hit ratio suddenly dropped, temp segment usage suddenly improving, physical read is increasing, etc.

If you are keen in system administration then you would get these all characteristics of performance bottleneck very quickly and easily. Because in Linux and Unix environment so many utilities available to monitor Oracle server accurately about usage and load. As per my own opinion, I always use system administration tools for server monitoring like "top" command or "vmstat" command. Those are best monitoring tools.

Oracle installs on operating system. We need to concentrate on server performance and system load. If server has too much load then obviously Oracle database performance would affect. There is no question about it. So many performance issues are starting from Oracle server consumption only. It is just like health of people. If your stomach is not healthy then you would get so many health problems at any part of body.

I got one very good article on performance tuning of Oracle server from a resource. Oracle Performance Tuning Troubleshooting is art and techniques. To get expertise in tuning, you need to get various kind of knowledge like system administration, network administration, hardware, and applications. Without that knowledge, it is very difficult to understand main reason behind server slowness. In another word we can say it "without knowledge of application, system, network, hardware, Oracle server tuning becomes mystery for you".

Enabling REMOTE_OS_AUTHENT and Security Risks in Oracle

An available approach is the use the “identified externally” account creation and set the parameter file parameter REMOTE_OS_AUTHENT to true. This approach enables and account that has been created using the same name as the client account to connect to the database via SQL*Net without the use of a password. Let’s say the account on a computer is identified with the name James and an account is created in the PROD database for “james identified externally”. James can now select SQL*Plus from his PC start/program menu and, at the username prompt, type and execute /@prod and connect to the SQL command line utility without giving password. If James is logged on directly to the operating system on which PROD is running, he can still just type sqlplus / to access database.

In the scenario in the last section, the security danger is that James will walk away from his PC without locking his terminal. Anyone would then be able to access the database without knowing James’s username and password and have James’s privileges on the system.

The second security risk is that you trust a remote operating system over which you may have no control. All somebody needs to do is determine an Oracle user in your database who has the desired role – including DBA – with an account that has been IDENTIFIED EXTERNALLY. Then, the person creates an account with the same username as the privileged database account, executes SQL*Plus, and BLA,BLA,BLA. That person is in your database with the highest possible privileges and there is nothing you can do, except set REMOTE_OS_AUTHENT=false.

These two security risks are biggest headache considering in Oracle services and database administration. We cannot eliminate these kinds of risk factors if we use REMOTE_OS_AUTHENT parameter without having knowledge and create operating system authentication user login in Oracle database. If we need to set this security then during remote dba services, it should be monitored regularly and audited.