excluding files from a merge

Our project has two main branches set up, one called 'development, and another called 'production'.

Each branch has a file in it called database.yml, (this is a rails project)...
 The development branch and the 
production branch are supposed to have different versions of this file. 
(and not only this file, but other 
config sorts of files as well, but this is a good example).

At the same time, when development is ready for deployment, we will do git checkout production git merge development

I would like it if every file was merged, except for files that were explictly excluded from a merge between these two branches. Is there a good way to do this?

-Daniel