[DRILL-7345] Strange Behavior for UDFs with ComplexWriter Output

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Not A Problem
• Affects Version/s: 1.17.0
• Fix Version/s: 1.17.0
• Assignee: Vova Vysotskyi
• Reporter: Charles Givre
• Created: 12/Aug/19 16:20
• Updated: 31/Jan/20 05:21
• Resolved: 13/Aug/19 08:58

Description

I wrote some UDFs recently and noticed some strange behavior when debugging them.
This behavior only occurs when there is ComplexWriter as output.

Basically, if the input to the UDF is nullable, Drill doesn't recognize the UDF at all. I've found that the only way to get Drill to recognize UDFs that have ComplexWriters as output is:

• Use a non-nullable holder as input
• Remove the null setting completely from the function parameters.

This approach has a drawback in that if the function receives a null value, it will throw an error and halt execution. My preference would be to allow null handling, but I've not figured out how to make that happen.

Note: This behavior ONLY occurs when using a ComplexWriter as output.