def num_physical_imei_shards(conn):
    """
    Helper function to return the number of physical shards for IMEI-shared partitions.

    Arguments:
        conn: dirbs db connection object
    Returns:
        number of physical imei shard in the schema
    """
    with conn.cursor() as cursor:
        cursor.execute('SELECT phys_shards FROM schema_metadata')
        return cursor.fetchone()[0]