Is it easy to switch from relational to non-relational databases with Rails?

Question

Good day,

I have been using Rails/Mysql for the past while but I have been hearing about Cassandra, MongoDB, CouchDB and other document-store DB/Non-relational databases. I'm planning to explore them later as they might be better alternative for scalability.

I'm planning to start an application soon. Will it make a different with Rails design if I move from relational to non-relational database? I know Rails migrations are database-agnostic but wasn't sure if moving to non-relational will make difference with design or not.

Answer 1

I think that MongoDB/MongoMapper are both mature enough now that you won't really notice the difference. This will be doubly true when these non-relational database ORMs move to using ActiveModel. This way, they'll all have the same underlying modules, which will help keep things consistent across your apps.

Answer 2

MongoMapper is mature enough to use in production (I am, for example). You can also use both ActiveRecord and MongoMapper models at the same time (I am doing that, too).

It's pretty simple to set up associations between them, as documented here: http://groups.google.com/group/mongomapper/browse_thread/thread/35d4acabf37e3984#

There is a rails3 branch of MongoMapper using ActiveModel. It will be part of the trunk eventually but for now you'd need to use this rails3 branch if you wanted to work with rails 3 from the get-go github.com/mharris717/mongomapper