I have used sql (mostly mysql) for years but not to a professional standard, so I'm looking for a shove in the right direction.

I am currently designing a web app that will collect user's names/addresses/emails etc in one set of tables, as well as other personal information in another set of tables. These would most naturally reside in one database, but I've been considering splitting the user contact information in one database on a separate server and all the other information into another database/server, the theory being that a hacker would have to break both systems to get anything very useful.

I've done searches off and on for a few weeks and haven't found this type of design discussed much so far. Is this generally done? Is it overkill? Is there a design method to approach it, or will I have to roll it all on my own?

I did find [Is splitting databases a legitimate security measure?](https://stackoverflow.com/questions/7158857/is-splitting-databases-a-legitimate-security-measure) which I guess is saying that this approach is likely overkill.