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https://issues.apache.org/jira/browse/AVRO-1340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15861056#comment-15861056
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Darryl Green commented on AVRO-1340:
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Anyone who needs this feature (the ability to extend enums) by definition needs
new implementations. As use of the feature is entirely optional I don't really
understand the rationale for this requiring an Avro 2.0 release. But ok. I'm
just looking for a way to get this to progress.
What WOULD be an acceptable change? I expect the pull request by [~ksenji] is
not ok in its current form as it changes the semantics of specifying a default
value; requires that any extensible enum have a default value (something it
wouldn't necessarily have); and requires that unknown values be mapped to the
default (I can easily imagine cases where the value I want to default to is not
the value I want if I read a value I don't expect). That said, its better than
no extensibility.
Whatever it is, I need it to actually make it into an Avro release and working
for multiple languages (C++, java and javascript) to truly solve my problem, so
guidance on what would potentially be acceptable would help....
> 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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