How to set different levels for different python log handlers

I needed a time to understand the point

1. Set the general logger below your subloggers (handlers) (your result of logging.getLogger())
2. Set your subloggers levels on an equal or superior level to your general logger

You can set a different logging level for each logging handler but it seems you will have to set the logger's level to the "lowest". In the example below I set the logger to DEBUG, the stream handler to INFO and the TimedRotatingFileHandler to DEBUG. So the file has DEBUG entries and the stream outputs only INFO. You can't direct only DEBUG to one and only INFO to another handler. For that you'll need another logger.

logger = logging.getLogger("mylog")
formatter = logging.Formatter(
    '%(asctime)s | %(name)s |  %(levelname)s: %(message)s')
logger.setLevel(logging.DEBUG)

stream_handler = logging.StreamHandler()
stream_handler.setLevel(logging.INFO)
stream_handler.setFormatter(formatter)

logFilePath = "my.log"
file_handler = logging.handlers.TimedRotatingFileHandler(
    filename=logFilePath, when='midnight', backupCount=30)
file_handler.setFormatter(formatter)
file_handler.setLevel(logging.DEBUG)

logger.addHandler(file_handler)
logger.addHandler(stream_handler)

logger.info("Started");
try:
    x = 14
    y = 0
    z = x / y
except Exception as ex:
    logger.error("Operation failed.")
    logger.debug(
        "Encountered {0} when trying to perform calculation.".format(ex))

logger.info("Ended");