[BEAM-12473] ClassCastException when using registerUdaf in Calcite SQL

• Type: Bug
• Status: Resolved
• Priority: P2
• Resolution: Fixed
• Affects Version/s: 2.31.0
• Fix Version/s: 2.32.0
• Component/s: dsl-sql
• Assignee: Jan Lukavský
• Reporter: Jan Lukavský
• Created: 10/Jun/21 09:41
• Updated: 15/Jun/21 08:22
• Resolved: 15/Jun/21 08:22

Description

When using registerUdaf as follows:

                .registerUdaf(
                    "LONGEST_WORD",
                    Max.of(
                        (Comparator<String> & Serializable)
                            (String a, String b) -> Integer.compare(a.length(), b.length()))))

results in following exception:

Caused by: java.lang.ClassCastException: class sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to class java.lang.Class (sun.reflect.generics.reflectiveObjects.TypeVariableImpl and java.lang.Class are in module java.base of loader 'bootstrap')
	at org.apache.beam.sdk.extensions.sql.impl.utils.CalciteUtils.sqlTypeWithAutoCast(CalciteUtils.java:327)
	at org.apache.beam.sdk.extensions.sql.impl.UdafImpl$1.getType(UdafImpl.java:73)
	at org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.prepare.CalciteCatalogReader.toOp(CalciteCatalogReader.java:315)
	at org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.prepare.CalciteCatalogReader.toOp(CalciteCatalogReader.java:302)
	at org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.prepare.CalciteCatalogReader.lambda$lookupOperatorOverloads$3(CalciteCatalogReader.java:271)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)

If this way of registering UDAF is not supported, it should throw a more user-friendly exception.

Issue Links

• duplicates: BEAM-11059 Cannot use generic class as UDAF implementation.
• links to: GitHub Pull Request #14986