How to Develop and Apply a Solution to Your Oracle 12c Errors - dummies

How to Develop and Apply a Solution to Your Oracle 12c Errors

By Chris Ruel, Michael Wessler

How do you fix a problem in your Oracle 12c database? Sometimes it is a simple command that is obvious even to the most inexperienced administrator. More commonly it is a multi-step operation that may span both database and non-database areas. Consider these guidelines as you develop and implement your plan.

For very simple and obvious fixes, you clearly aren’t going to apply every step listed in the following exhaustive detail. However, you should review the guidelines and see how they apply to what you’re doing.

How to research your Oracle 12c errors

You should understand what is happening and why. What is causing the problem and how is that best remedied?

  • Review the error messages.

  • Read the documentation.

  • Search the Internet.

  • Talk to other administrators.

  • Get Oracle Support assistance.

It’s dangerous to apply a fix when you don’t know why something is occurring. Only through understanding will you have the confidence that whatever fix you apply is the right one and won’t cause further damage.

How to make plan to fix Oracle 12c errors

How will you specifically fix the problem? After creating your high-level plan, make it technically detailed:

  • Identify the technical substeps for each high-level pseudo-code step.

  • Know what commands need to be issued and by which account.

  • Know the time necessary for each step to occur and dependencies between steps.

  • If additional software or patches are required, make sure those needs are addressed.

Have another administrator review your fix-planning steps to make sure you haven’t skipped anything.

Basic ramifications of Oracle 12c errors

If you perform the fix, what are the side effects?

  • Will you have to restart and place the system in restricted session for a complex fix, kicking off system users?

  • How long will the system be unavailable? Remember to leave yourself a margin for error and unexpected issues.

  • When is the best downtime to impose a reduced impact on end users while still having outside support if needed?

  • Can you perform the fix solo, from end to end, or do you need help from other groups (such as networking or the system administrator)?

  • Does the fix void your software warranty or break other components?

    Unfortunately, not all solutions are easy decisions and sometimes there are downsides to a fix. Carefully weigh the benefits of a fix and the negatives of the existing problem against the downsides of implementing the fix.

Coordinating with other groups and the user community for a fix is often a big hurdle when working on large, distributed, and complex systems.

How to test situations that cause Oracle 12c errors

If at all possible, re-create the problem in a test environment and apply the fix there before doing it in production.

Testing accomplishes these things:

  • Ensures your steps are complete

  • Provides accurate timeframes for the total fix

  • Verifies your syntax with the opportunity to make mistakes

  • Confirms the problem is actually fixed

  • Verifies there are no unintended consequences

Many organizations are under mandate to test changes before going into production, and that is generally a good policy. When you’re troubleshooting complex problems or operating on large amounts of data, testing is even more important.

We’ve seen many ill-advised attempts at applying untested fixes that ended in disastrous results. Don’t let that happen to you.

Fallback options when Oracle 12c errors go unresolved

The fix doesn’t work and things go from bad to worse. You do have a fallback plan, right? A good administrator always has a workable fallback plan for when things go wrong. Those who don’t, sooner or later, end up seeking other employment opportunities.

Before performing nearly any technical fix, do these things:

  • Take another database backup or verify that your most recent backups are valid and accessible.

  • If backups are stored offsite for disaster recovery, recall those backups. You may need them before you start your maintenance operation.

  • Consider taking multiple backup copies too, in case one copy is bad. Parachutists jump with a backup chute; shouldn’t you?

After large amounts of data have been modified, can it be undone without a backup? You may need to work with the application developers on data changes. Also consider other items that need to be undone outside the database.

For example, a network change with DNS may require several hours to take effect. If you push a change to thousands of client workstations, how do you roll that back if necessary?

Support for Oracle 12c errors

Odds are good that you’ll be performing your maintenance over a weekend or late at night. If so, are the other people available to perform their parts of the fix?

  • Do you have everyone’s phone numbers?

  • Are they willing and able to help you at 3 a.m. when you discover a problem? Be sure to let them know you may require their assistance before you start your work.

  • Are they authorized to make the change?

How to verify fixes for Oracle 12c errors

Who is going to test and confirm the fix actually worked? A test plan with testers or knowledgeable users is a good idea, particularly if data or application changes are necessary.

  • Run through the plan first; otherwise you may discover broken parts of the application unrelated to the problem you’re attempting to fix.

  • Make sure these testers are available when you’re done with your work.

How to backup Oracle 12c data

After you’ve developed, tested, applied, and verified your technical fix, what’s the final step before turning it over to the users? Often the final step is performing a full database or system backup. The benefit is that if something unrelated occurs and you need to restore, you don’t need to go through the previous fix.