[TAJO-2089] Improve null handling in UDF

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.12.0, 0.11.2
• Component/s: Function/UDF
• Assignee: Jinho Kim
• Reporter: Jinho Kim
• Created: 07/Mar/16 05:44
• Updated: 08/Mar/16 08:26
• Resolved: 08/Mar/16 07:15

Description

A null value should convert to NullDatum in UDF. if not, it throw a TajoInternalError. Many people mistake the null handling.
So we add null handling, it would be better