Oracle troubleshooting is an advanced concept, but step-by step directions are available for proper troubleshooting of Oracle performance problems.  For a complete reference on Oracle troubleshooting, see the book "Oracle Troubleshooting" by Robin Schumacher.

Oracle has become the world's most sophisticated and flexible database, and the sheer complexity of Oracle makes it very difficult to troubleshoot. 

So, how can you learn Oracle troubleshooting skills?  First, I recommend that students have a strong background in the internal machinations of Oracle, and understand the underlying mechanisms of the Oracle engine.  It's also important to recognize how Oracle alerts us to problems, and how to interpret error messages.

When an end-user is hung, the problem could be system-wide or unique to their session, and it's up to the Oracle DBA to understand the right questions to ask and know the right places to look for further information. 

The goals of Oracle troubleshooting

The goals of Oracle troubleshooting include:

* Learn a troubleshooting methodology for use in analyzing any Oracle database

* Understand ratio-based and bottleneck troubleshooting analysis

* Learn troubleshooting techniques for monitoring and optimizing memory usage

* Know how to quickly pinpoint and resolve I/O hotspots at the database, storage and object level

* Using scripts to uncover session-related bottlenecks

* Understand techniques for locating and fixing problem SQL

Here are some specific troubleshooting techniques for diagnosing acute Oracle performance issues.  There are also specific tip for Oracle troubleshooting that can guide a neophyte in the right direction:

* Always check the first error message - Oracle will frequently throw multiple errors, but it's always the first error that will lead you to the root cause of the problem.

* Root cause analysis is not always practical - You may need to forget what you learned in Oracle University Performance Tuning Training.  In a real emergency you may not have the luxury of addressing the root cause of a performance problem.  One hallmark of a successful Oracle troubleshooter is the prudent application of unconventional techniques.

* Know your OFA structure - You need to be intimate with your OFA directories on the server so that you can quickly locate trace files and dumps from Oracle problems when troubleshooting.

* Don't be afraid to  bounce - If you have a system-wide outage and you cannot connect to the database, you may want to quickly attempt to collect trace dumps and bounce the instance immediately.  In the vast majority of system-wide hanging that is related to memory issues, a bounce will quickly restore database access.  This can be an invaluable troubleshooting tool.

Oracle troubleshooting tips

Most effective DBA's have a strong ?meld? of technical and managerial skills and this helps them become effective detectives. 
 
This dual strength of technical and business acumen is indispensible for troubleshooting an Oracle database because you must understand every layer of an application, from the mapping to the business processes to screens, all the way down to the internals of the row placement on disk!
 
In additional to spending years in college getting advanced degrees (often in the areas of computer science or information systems) Oracle troubleshooting experts are now expected to meld-together this huge body of learning into a cohesive method for diagnosing and troubleshooting a wide variety of data related problems!
 
One of the most stressful aspects of the Oracle DBA job role is troubleshooting and acute performance problem.  In a serious emergency, there could be thousands of end-users waiting for the DBA to give them access to their database and you are right at the center of the problem!  During a production troubleshooting session you will meet all sorts of high-level executives, all impatient and looking at their watches, continue the downtime costs and encouraging you to work faster!
 
While the proactive techniques described in this book serve to prevent future performance problems, there is always the possibility of a rare exception, a rogue process, or an unplanned increase in system usage.
 
It is also important to understand the scope of unplanned outages.  The DBA may be troubleshooting a locked session for a single end-user, or could be troubleshooting a system-wide outage that affects thousands of end-users.

While it's not practical to reproduce the entire Oracle Troubleshooting book on this page, here are some specific Oracle troubleshooting tips and tricks: