Thanks Jacques. Appreciate your response. On Tue, Jan 5, 2016 at 10:59 PM, Jacques Nadeau <jacq...@dremio.com> wrote:
> The default behavior of Drill UDFs is NullHandling.NULL_IF_NULL semantics. > This means that a the Drill engine manages checking nullability on inputs. > If one or more inputs is null, then the output is null. You can also > implement NullHandling.INTERNAL as your null semantics in a UDF. This > allows you to set nullability on your output independent of the nullability > of the inputs. An example is the isNull functions [1]. Note that the > complexity with using internal handling if you have to create > implementations for all variations of null inputs and outputs. This is the > cartesian product of variations when you have multiple parameters. As such, > we generally use freemarker templates (per the example below) to create the > variations. > > [1] > > https://github.com/apache/drill/blob/master/exec/java-exec/src/main/codegen/templates/NullOperator.java > > -- > Jacques Nadeau > CTO and Co-Founder, Dremio > > On Mon, Jan 4, 2016 at 8:04 PM, Nirav Shah <nirav.s...@games24x7.com> > wrote: > > > Hi, > > May be this is silly question, Please let me know how to return null > string > > from drill custom function. > > > > > > Regards, > > Nirav > > >
