MetaContent

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.

Installation

Add to your Gemfile

gem 'meta_content'

Data

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.

Usage

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)

Fast, Slow, Huh?

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.

Scalability

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.