Recently a colleague of mine wanted my opinion on a situation he discovered with one of his clients. This client had an Oracle Database server with one database configured which was beeing used by multiple applications. He thought it wasn’t a good idea but wanted to hear my opinion on this. This is what I told him.

1. performance

Which application is causing bad performance? Monitoring separate databases is much simpler to setup than monitoring use on separate tables or weeding through all logging to see which parts of the database get pounded.

2. scaling

This is one possible next step when performance issues arrive. You want to split applications over different physical servers. In this setup you would have to do a lot of work getting data exported and imported in a new database. If the databases had been separate, you’d be better of.

3. upgrading and version incompatibility

You will encounter the application upgrade that depends on a newer database version. What happens if another one just can’t work with the new version? You will have to split the apps over different servers anyways. Better be prepared and use separate databases

4. licensing issues

You may not have enough licenses to create more databases. I’m not familiar with the licensing schemas Oracle uses. As far as I know this is processor based, not database based. People might not know and prevent issues by putting everything in the same database. Not a good idea. Sort out your licensing issues and pay the fee if you need to. Else, select applications that can use open source database platforms to save a penny or two…

5. security between apps

It’s very well possible to prevent users of different applications peeping in the tables of other applications. This setup is however more complicated than just splitting the data over different applications with their own separate access controls. Internal espionage is the most common form as you may know. Don’t take a chance here and don’t overcomplicate things.

In general I would say you would need some severe reasons to choose such a solution. Tell me what you think. Did I miss a point, Are there good reasons to do it this way?

I hope you liked this post. If you do, (or don’t) don’t hesitate to comment.