diff options
Diffstat (limited to 'python')
| -rw-r--r-- | python/pyspark/sql/functions.py | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py index dac842c0ce..716b16fdc9 100644 --- a/python/pyspark/sql/functions.py +++ b/python/pyspark/sql/functions.py @@ -1756,6 +1756,9 @@ class UserDefinedFunction(object): @since(1.3) def udf(f, returnType=StringType()): """Creates a :class:`Column` expression representing a user defined function (UDF). + Note that the user-defined functions must be deterministic. Due to optimization, + duplicate invocations may be eliminated or the function may even be invoked more times than + it is present in the query. >>> from pyspark.sql.types import IntegerType >>> slen = udf(lambda s: len(s), IntegerType()) |