class ActiveRecord::Migration::Compatibility::V4_2

def index_exists?(table_name, column_name, **options)
  column_names = Array(column_name).map(&:to_s)
  options[:name] =
    if options[:name].present?
      options[:name].to_s
    else
      connection.index_name(table_name, column: column_names)
    end
  super
end