[jira] [Commented] (AVRO-1340) use default to allow old readers to specify default enum value when encountering new enum symbols

["Zoltan Farkas (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AVRO-1340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15173944#comment-15173944 ] 

Zoltan Farkas commented on AVRO-1340:
-------------------------------------

Taking the default value when receiving a undefined value is most likely not optimal.

enhancing current enum to something like:

{code}
enum Suit {
  SPADES, DIAMONDS, CLUBS, HEARTS, @undefined UNDEFINED 
}
{code}

where the undefined attribute will mark the enum val to use to resolve values that cannot be recognized?


> 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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