Having some issues on backend regarding a social networking project on ROR

I am working on a social networking project. I need to store about 10-15 user profile information like movies,music,books,relationship-status and so on. I am confused about which database should i use to store user profile info. There are NOSQL solutions like MONGODB as well as Neo4j(graph). Or should i store it in relational database like mysql. Needless to say, but the solution should be scalable and efficient. Any guidance on this would be of great help.

The information would seem to fit a RDMS perfectly. But then as you have not given us any idea as to how simple or complex you expect this data to be no one can tell. Tell us what the data is like and we will be able to give you a better answer.

Thanx for your reply.My problem is that at a later point of time this would account for very large data set as the users will increase. I want to optimize my website and want to save time on data query from the database.Also, i will be looking for similar user profile based on user’s attribute like(taste in music,movies,interests etc).I want this to be done very efficiently and in a proper manner so that there is less complexity in writing the code.

I think the User->HasOne->Profile association will be OK. From there you can go searching for more efficient database calls.

I would suggest MongoDB is a right choice…

Having a large amount of simple data is not the same problem as having
complex data. If all you are storing is key value pairs you could have a
table like this

class Interest < ActiveRecord::Migration
  def change
    create_table :interests do |t|
      t.integer :user_id, :null => false
      t.string :type, :null => false
      t.string :value, :null => false
      t.timestamps
    end
  end
end

And you would store it as:

Interest.create(:user_id => user.id, :type => 'music', :value => 'Status
Quo')
Interest.create(:user_id => user.id, :type => 'movie', :value => 'The Color
Purple')
Interest.create(:user_id => user.id, :type => 'hobby', :value => 'Fishing')
Interest.create(:user_id => user.id, :type => 'food', :value => 'Cheese')

and have a has_many link from the User model to retrieve the data. This
sort of data is exactly what an RDBMS is best suited for. Of course if it
is just key value pairs then something like Redis is also a good tool too.

MongoDBs strength is document storage for unstructured data. The problem is
that the data you have is neither a document nor unstructured. This is not
to say that you cannot store key value pairs in MongoDB but it is not the
best tool for the problem you describe.

Ok I got your point behind not using Mongodb. But the project is similar to facebook and facebook uses graph. So, what advantage can one get by using graph. And why shouldn’t I use graph for this project. In this project, users will post status updates too and those updates will have tags. So think of a share model that has like 5 tags. So, should I create a tag model and then a share has many tags, or is there a better solution?

Don’t fool yourself into thinking that Facebook is using a single data store. Facebook has a massive set of resources Remember that they have their own PHP compiler.

They are most certainly using multiple data stores redundantly and querying the right one for the job at hand for each particular piece of functionality.

So for the job at hand, what do you suggest? Mysql or graph?