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https://issues.apache.org/jira/browse/FLINK-6024?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Flink Jira Bot updated FLINK-6024:
----------------------------------
Labels: auto-deprioritized-major stale-minor (was:
auto-deprioritized-major)
I am the [Flink Jira Bot|https://github.com/apache/flink-jira-bot/] and I help
the community manage its development. I see this issues has been marked as
Minor but is unassigned and neither itself nor its Sub-Tasks have been updated
for 180 days. I have gone ahead and marked it "stale-minor". If this ticket is
still Minor, please either assign yourself or give an update. Afterwards,
please remove the label or in 7 days the issue will be deprioritized.
> Need more fine-grained info for "InvalidProgramException: This type (...)
> cannot be used as key"
> ------------------------------------------------------------------------------------------------
>
> Key: FLINK-6024
> URL: https://issues.apache.org/jira/browse/FLINK-6024
> Project: Flink
> Issue Type: Improvement
> Components: API / Type Serialization System
> Affects Versions: 1.2.0
> Reporter: Luke Hutchison
> Priority: Minor
> Labels: auto-deprioritized-major, stale-minor
>
> I got this very confusing exception:
> {noformat}
> InvalidProgramException: This type (MyType) cannot be used as key
> {noformat}
> I dug through the code, and could not find what was causing this. The help
> text for type.isKeyType(), in Keys.java:329, right before the exception is
> thrown, says: "Checks whether this type can be used as a key. As a bare
> minimum, types have to be hashable and comparable to be keys." However, this
> didn't solve the problem.
> I discovered that in my case, the error was occurring because I added a new
> constructor to the type, and I didn't have a default constructor. This is
> probably quite a common thing to happen for POJOs, so the error message
> should give some detail saying that this is the problem.
> Other things that can cause this to fail, including that the class is not
> public, or the constructor is not public, or the key field is not public, or
> that the key field is not a serializable type, or the key is not Comparable,
> or the key is not hashable, should be given in the error message instead,
> depending on the actual cause of the problem.
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