function(doc) {
  var json = JSON.stringify(doc);
  emit(json.length, null);
}

function(doc) {
  var json = JSON.stringify(doc);
  emit(json.length, null);
}

function(doc) {
  var json = JSON.stringify(doc);
  var len = json.length;
  if (doc._attachments) {
    for (var attachmentKey in doc._attachments) {
      var attachment = doc._attachments[attachmentKey];
      len += attachment.length;
    }
  }
  emit(len, null);
}