[DRILL-975] Null-on-exception option for cast functions

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Fix Version/s: Future
• Component/s: Functions - Drill
• Assignee: Unassigned
• Reporter: Steven Phillips
• Created: 12/Jun/14 18:32
• Updated: 05/Feb/16 15:45
• Resolved: 28/Dec/14 22:45

Description

Currently, if a particular value cannot be cast to the target type, an exception is thrown and the query fails. We should have a mode that will treat the output of all cast functions as nullable, and return a null value if the cast fails, rather than throwing an exception.

An important example where this is important is when using the Text reader. The text reader always produces a single, RepeatedVarChar column. The columns are then cast to the appropriate type. For the columns that are cast to numeric types, if there is no value (i.e. it's an empty string), currently this will throw NumberFormatException. What we really want is for it to produce a Null value.

Issue Links

• is duplicated by: DRILL-1430 sum(cast(columns[0] as int)) fails if column contains empty value
• is duplicated by: DRILL-986 Explicit cast of empty string to double/integer throws NumberFormatException