Fast and queryable schemaless MySQL. MetaContent stores attributes of your model across multiple rows in a separate table. It allows you to treat attributes as ancillary data rather than incurring the load of initializing or storing them upon update.

Add to your Gemfile

gem 'meta_content'

Create a table for your class

rails g meta_content [your_class_name]
rails g meta_content user

This will create a table named [your_class_name]_meta. This table will hold the meta attributes for the class as soon as you include the MetaContent module into it.

Include the MetaContent module into your class.

class User < ActiveRecord::Base
  include MetaContent
  # ...
end	

Then describe the attributes using meta blocks:

class User < ActiveRecord::Base

  meta do
    string :my_field
  end
	
  meta :scoped_meta do
    integer :visitor_count
    string  :visit_path
    
    meta :subscoped_meta do
      range :visitor_ages
    end
  end

end

Now you can access these attributes in the following way:

u = User.new

u.my_field = 'test'
u.my_field
# => 'test'

u.meta
# => {:my_field => 'test'}

u.scoped_meta
# => <MetaContent::Proxy …>

u.scoped_meta.visitor_count = 30
u.scoped_meta.visitor_count
# => 30

u.scoped_meta__visitor_count
# => 30
u.scoped_meta.meta
# => {:visitor_count => 30}

u.scoped_meta = {:visitor_count => 3, :visit_path => '/test'}
u.scoped_meta__visitor_count
# => 3

u.scoped_meta__subscoped_meta__visitor_ages = (30..40)
u.scoped_meta__subscoped_meta__visitor_ages
# => (30..40)
u.scoped_meta.subscoped_meta.visitor_ages
# => (30..40)

You'll notice accessors are provided for all meta content, even if it's scoped. You can apply this data just like any other attribute:

User.new(:scoped_meta__visitor_count => 3)

It's fast. It uses MySQL's ON DUPLICATE KEY UPDATE syntax to only ever conduct 1 or 2 queries when changes are made. If no changes are made, nothing is written. Unlike serialized content, it will not impact your table's performance.

Not sure what the upper limit of this statement is but up through a few million records in the meta table I've seen no change in query times. I'll try to push this up to a few hundred million records and try again at some point.