class EltChildrenCount < ActiveRecord::Migration
  def self.up
		add_column :elts, :elts_count, :integer, :default => 0
		execute 'UPDATE elts SET elts_count = (SELECT COUNT(*) FROM elts e2 WHERE e2.parent_id = elts.id)'
		add_index "elts", ["lft"], :name => "elts_lft_key", :unique => true
		add_index "elts", ["parent_id"], :name => "elts_parent_key"
  end

  def self.down
		remove_column :elts, :elts_count
  end
end