Spark >= 2.3
It is possible to disable some optimizations using
import org.apache.spark.sql.expressions.UserDefinedFunction val f: UserDefinedFunction = ??? val fNonDeterministic: UserDefinedFunction = f.asNondeterministic
Please make sure you understand the guarantees before using this option.
Spark < 2.3
Function which is passed to udf should be deterministic (with possible exception of SPARK-20586) and nullary functions calls can be replaced by constants. If you want to generate random numbers use on of the built-in functions:
rand– Generate a random column with independent and identically distributed (i.i.d.) samples from U[0.0, 1.0].
randn– Generate a column with independent and identically distributed (i.i.d.) samples from the standard normal distribution.
and transform the output to obtain required distribution for example:
(rand * Integer.MAX_VALUE).cast("bigint").cast("string")