I have used rails and gem(acts as taggable on). I want to change acts as taggable on's database setting. so,I set as below -database.yml default: &default adapter: mysql2 database: my_db1 host: localhost username: root password: pass development: <<: *default my_db2: <<: *default database: my_db2 -user_model.rb class User < ActiveRecord::Base acts_as_taggable establish_connection :my_db2 end and,