Moving from SQLite3 to Mongo on Heroku?

I'm currently using SQLite3 with a simple post and image sharing app, similar to the Rails 3 Hartl tutorial (in terms of db structure). But I'd like to move to Mongo for future scalability/learning.

I'm also hosted on Heroku, and am using a 15 GB开发者_如何学JAVA shared db. I attempted to install MongoHQ and MongoMapper (as per Heroku's instructions) for the transition and this part according to Heroku's support is set up correctly. However, when I turn off the shared db, the app stops working, rather than running off of Mongo.

I'm not sure what do do next, do I have to rewrite my code in mongo or does mongo mapper solve all that? Do I lose my data if I change, if so, how do I copy?

Could any of you please point me to some resources or help me out? Thank you very much!!

MongoDB is not a drop in replacement for a SQL database. There are a couple of things you need to adapt:

• The models' code are to be updated to use MongoDB. I can suggest using Mongoid, an ODM, as it will ease your learning path. Mongoid implements Active Record.

• The current data saved in your SQL database needs to be migrated - and this is not automatic – to MongoDB schemas. MongoDB do not support migrations as you are used to in SQL world. You will need to write your own scripts for that.

I suggest you write a simple app from scratch using your MongoDB ODM of choice – MongoMapper or Mongoid – so that you get familiar with the basis of MongoDB before attempting to make a migration.