[IMPALA-12184] Java UDF increment on an empty string is inconsistent

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 4.3.0
• Fix Version/s: Impala 4.3.0
• Epic Link: Java11
• Epic Color: ghx-label-3
• Assignee: Peter Rozsa
• Reporter: Michael Smith
• Created: 02/Jun/23 18:18
• Updated: 24/Jun/23 12:26
• Resolved: 20/Jun/23 17:01

Description

Java 8 and Java 11 seem to match different signatures for select increment("");, and one is implemented to return null for empty string while the other ends up returning empty string.

When passed a string, which signature of BufferAlteringUdf matches it appears to be arbitrary: in Java 8, Class.getMethods() returns the BytesWritable signature first (and the Thrift STRING type fits that signature) while in Java 11 it returns the Text signature first (which Thrift STRING type also matches).

This causes failures in query_test.test_udfs.TestUdfExecution.test_java_udfs (e.g. https://jenkins.impala.io/job/ubuntu-20.04-from-scratch-java11/11/).

Issue Links

• is caused by: IMPALA-11854 ImpalaStringWritable's underlying array can't be changed in UDFs