class UniqueUserUrls < ActiveRecord::Migration
    def self.up
        # do last registered ones first, so the last ones get rubbish URLs
        User.find(:all, :order => "id desc").each do |user|
            user.update_url_name
            user.save!
        end
        # MySQL cannot index text blobs like this
        if ActiveRecord::Base.connection.adapter_name != "MySQL"
            remove_index :users, :url_name
            add_index :users, :url_name, :unique => true
        end
    end

    def self.down
        # MySQL cannot index text blobs like this
        if ActiveRecord::Base.connection.adapter_name != "MySQL"
            remove_index :users, :url_name
            add_index :users, :url_name, :unique => false
        end
    end

end