redmine/db/migrate/20091220183509_add_lft_and_rgt_indexes_to_projects.rb

class AddLftAndRgtIndexesToProjects < ActiveRecord::Migration[4.2]
  def self.up
    add_index :projects, :lft
    add_index :projects, :rgt
  end

  def self.down
    remove_index :projects, :lft
    remove_index :projects, :rgt
  end
end