Active Record Schema

Allows programmers to programmatically define a schema in a portable DSL. This means you can define tables, indexes, etc. without using SQL directly, so your applications can more easily support multiple databases.

Usage:

  ActiveRecord::Schema.define do
    create_table :authors do |t|
      t.string :name, :null => false
    end

    add_index :authors, :name, :unique

    create_table :posts do |t|
      t.integer :author_id, :null => false
      t.string :subject
      t.text :body
      t.boolean :private, :default => false
    end

    add_index :posts, :author_id
  end

ActiveRecord::Schema is only supported by database adapters that also support migrations, the two features being very similar.