As an implementer of commercial and open source database monitoring tools I find DatabaseRX has capabilities that clearly differentiate it from the rest of the market:

Scalability - hundreds of databases and instances can be added with trivial monitoring overhead, due in part to a highly normalized data model, message based architecture and modular design (loader,analyzer,notifier).
Security [...]

Googling is an essential DBA skill. The Internet is a treasure trove of information that can help you in solving a problem. For example, user groups such as the Northern California Oracle Users Group (NoCOUG) have made vast collections of electronic presentations and white papers available on their web pages. Often a simple Google search [...]

 
Most Oracle professionals who focus on performance optimization are familiar with Method-R, which Cary Millsap tirelessly promotes.  Briefly stated, this method focuses on a specific process which is not performing satisfactorily.  We trace the process and see precisely what the process is doing.
 
We recently had a problem in which client connections were failing about half [...]