Boto3 is_in在扫描操作中不起作用

Question

我正在尝试对表中的键值进行扫描，它在查询中工作正常，但在扫描中却无法正常工作。我想念什么吗？

def get_items_from_id_list(id_list, table_name, key_name):
  #setup resource
  table = get_dynamo_table(table_name, dynamodb_region_name)

  # scan
  condition_expression = Attr(key_name).is_in(id_list)
  result = table.scan(FilterExpression=condition_expression)

  # query for 1
  query_expression = Key(key_name).eq(id_list[0])
  result2 = table.query(KeyConditionExpression=query_expression)

  # !! result contains 0 items
  # !! result2 contains 1 item

  if not result.get('Count'):
    return []
  out = result['Items']
  del out['aws:rep:updatetime']
  return out