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https://issues.apache.org/jira/browse/AVRO-1340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15571887#comment-15571887
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Zoltan Ivanfi commented on AVRO-1340:
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I agree that the generic fallback mechanism may be overkill, I just argued that
even though it is not useful for card suits, it can make sense with different
types of enums.
My main concern about introducing a default value for unknown values is that 1)
it requires writing boiler-plate code, but 2) this requirement is not enforced
and if the boiler-plate is not added initially it is impossible to handle the
situation later. On the other hand, even with these shortcomings, the
possibility to specify a default value is still better than the current
situation.
> use default to allow old readers to specify default enum value when
> encountering new enum symbols
> -------------------------------------------------------------------------------------------------
>
> Key: AVRO-1340
> URL: https://issues.apache.org/jira/browse/AVRO-1340
> Project: Avro
> Issue Type: Improvement
> Components: spec
> Environment: N/A
> Reporter: Jim Donofrio
> Priority: Minor
>
> The schema resolution page says:
> > if both are enums:
> > if the writer's symbol is not present in the reader's enum, then an
> error is signalled.
> This makes it difficult to use enum's because you can never add a enum value
> and keep old reader's compatible. Why not use the default option to refer to
> one of enum values so that when a old reader encounters a enum ordinal it
> does not recognize, it can default to the optional schema provided one. If
> the old schema does not provide a default then the older reader can continue
> to fail as it does today.
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