Side Outputs#


An OutputTag is a typed and named tag to use for tagging side outputs of an operator.


# Explicitly specify output type
>>> info = OutputTag("late-data", Types.TUPLE([Types.STRING(), Types.LONG()]))
# Implicitly wrap list to Types.ROW
>>> info_row = OutputTag("row", [Types.STRING(), Types.LONG()])
# Implicitly use pickle serialization
>>> info_side = OutputTag("side")
# ERROR: tag id cannot be empty string (extra requirement for Python API)
>>> info_error = OutputTag("")