Verbose Oracle RDBMS error log output examples

It looks like the hardening was a little to hard. Oracle does need some access to the server. You can revert back the chmods for ping, Oracle rdbms does not need it. /tmp/ is not required, a usable location for tmp is, mostly for scripting. The rdbms has it's own tricks and storage for sorts.

Never install Oracle as root; use the root.sh at the end of the installation to do the system tweeks required. On some platforms there is a root pre script that should run before installation. The Oracle installation scripts refuse to run using the root account and can be run using any other account.

The access to some server config files has been made a little too tight for the install user to check the prerequisites. If you know they are ok, it's ok. Proving they are ok is a little easier when support issues arise. Check the group ownership of the critical config files and add the Oracle installation user to that group to give it read access.

If the unique field is properly indexed, a UNIQUE violation should be fairly quick.

Honestly though, I think doing a "two inner select" (I think I know what you mean here) is a better solution. Even with trapping for an exception (at the application level), that's just not a very clean way to handle programatic logic. Exception handling should be reserved for those rare occasions where you have an "exception to the rule."

And (without knowing which language you're coding in) if you're just trapping for a "SQLException", it's important to remember that those can be thrown for a variety of reasons. Your application might produce unexpected results if you incorrectly assume why an exception happened.

Bottom-line, I would say that the best approach is to do the SELECT to check for duplication.