Users.where(country_id: 44).as_batches(:batch_size=>200) do |user|
    user.party_all_night!
  end

ar-as-batches is what you (might) need if you were hoping #find_each would solve your problem and are disappointed to find that it doesn't.

Like #find_each it is intended for batch processing of large (or unknown) numbers of records that would require excessive memory if an object for each of the complete result set were created at once. It retrieves records from your relation in batches of 1000 (or as specified by the :batch_size option) and yields each record.

Unlike #find_each it honours order, limit and offset options on your query, so if you want records in reverse chronological order instead of ascending id order, and you want to start on page 2: you're welcome.