[DRILL-2118] Improve error message to inform the user if mappify/kvgen fails due to ClassCastException

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.9.0
• Component/s: Functions - Drill
• Assignee: Mehant Baid
• Reporter: Hanifi Gunes
• Created: 29/Jan/15 19:04
• Updated: 04/Mar/15 02:34
• Resolved: 04/Mar/15 02:34

Description

Currently mappify throws a non-user friendly error message when the input map consists of heterogenous value types. The proposal is to improve the error message to inform user about the usage and root cause of the failure in a non-technical dialect.

Running

select kvgen(t.m) from ex.json t

over

ex.json

{m:{a:1}}
{m:{b:-1.0}}

throws

Query failed: Query failed: Failure while running fragment., org.apache.drill.exec.vector.complex.impl.NullableFloat8WriterImpl cannot be cast to org.apache.drill.exec.vector.complex.impl.NullableIntWriterImpl

We should inform the user with an intelligible reason why the query failed instead.

Issue Links

• duplicates: DRILL-2112 Throw helpful error message with unsupported KVGen functionality