demo_app/my_platform/db/migrate/20161011140943_add_missing_taggable_index.your_platform.rb
# This migration comes from your_platform (originally 20161011140816)
# This migration comes from acts_as_taggable_on_engine (originally 4)
class AddMissingTaggableIndex < ActiveRecord::Migration[4.2]
def self.up
add_index :taggings, [:taggable_id, :taggable_type, :context]
end
def self.down
remove_index :taggings, [:taggable_id, :taggable_type, :context]
end
end