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https://issues.apache.org/jira/browse/BEAM-12473?focusedWorklogId=609653&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-609653
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ASF GitHub Bot logged work on BEAM-12473:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 10/Jun/21 11:23
Start Date: 10/Jun/21 11:23
Worklog Time Spent: 10m
Work Description: je-ik commented on pull request #14986:
URL: https://github.com/apache/beam/pull/14986#issuecomment-858538776
I'm not 100% sure this is the best solution. We should definitely not throw
ClassCastException in the described case. My first iteration was to simply
throw an exception explaining why this doesn't work, but then I realized, that
by wrapping into anonymous subclass the problem can be solved. Not sure if the
anonymous subclass should be created as well, but looks reusable and actually
helps a lot (at least with JDK11+, where it is possible to create anonymous
subclasses with diamond operator, so the user does not actually know that the
accumulator of Max is `Combine.Holder<T>`, which is nice).
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Issue Time Tracking
-------------------
Worklog Id: (was: 609653)
Time Spent: 20m (was: 10m)
> ClassCastException when using registerUdaf in Calcite SQL
> ---------------------------------------------------------
>
> Key: BEAM-12473
> URL: https://issues.apache.org/jira/browse/BEAM-12473
> Project: Beam
> Issue Type: Bug
> Components: dsl-sql
> Affects Versions: 2.31.0
> Reporter: Jan Lukavský
> Assignee: Jan Lukavský
> Priority: P2
> Time Spent: 20m
> Remaining Estimate: 0h
>
> When using {{registerUdaf}} as follows:
> {code:java}
> .registerUdaf(
> "LONGEST_WORD",
> Max.of(
> (Comparator<String> & Serializable)
> (String a, String b) ->
> Integer.compare(a.length(), b.length()))))
> {code}
> results in following exception:
> {noformat}
> 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)
> {noformat}
> If this way of registering UDAF is not supported, it should throw a more
> user-friendly exception.
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