Warns if MySQL log file size is not large enough for blob insertions.

def _CheckLogFileSize(cursor):
  """Warns if MySQL log file size is not large enough for blob insertions."""

  # Do not fail, because users might not be able to change this for their
  # database. Instead, warn the user about the impacts.

  innodb_log_file_size = int(_ReadVariable("innodb_log_file_size", cursor))
  required_size = 10 * mysql_blobs.BLOB_CHUNK_SIZE
  if innodb_log_file_size < required_size:
    # See MySQL error 1118: The size of BLOB/TEXT data inserted in one
    # transaction is greater than 10% of redo log size. Increase the redo log
    # size using innodb_log_file_size.
    max_blob_size = innodb_log_file_size / 10
    max_blob_size_mib = max_blob_size / 2**20
    logging.warning(
        "MySQL innodb_log_file_size of %d is required, got %d. "
        "Storing Blobs bigger than %.4f MiB will fail.", required_size,
        innodb_log_file_size, max_blob_size_mib)