Contents

class CreateTags < ActiveRecord::Migration
  def change

    create_table :tags do |t|
      t.string :name
      t.integer :parent_id
      t.timestamps
    end

    create_table :tags_hierarchies, :id => false do |t|
      t.integer :ancestor_id, :null => false # ID of the parent/grandparent/great-grandparent/... tag
      t.integer :descendant_id, :null => false # ID of the target tag
      t.integer :generations, :null => false # Number of generations between the ancestor and the descendant. Parent/child = 1, for example.
    end

    # For "all progeny of..." selects:
    add_index :tags_hierarchies, [:ancestor_id, :descendant_id], :unique => true

    # For "all ancestors of..." selects
    add_index :tags_hierarchies, :descendant_id

  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
closure_tree-1.0.0.beta2	test/dummy/db/migrate/20110522004834_create_tags.rb
closure_tree-1.0.0.beta1	test/dummy/db/migrate/20110522004834_create_tags.rb