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https://issues.apache.org/jira/browse/AVRO-1340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15571571#comment-15571571
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Zoltan Farkas commented on AVRO-1340:
-------------------------------------

Agree, fallback and alias are different concepts. Alias implies that it is the 
same thing with a different name.

The more I think, I think using the default value declared for the field is the 
better way.

for example in v1:

{code}
enum Suit {
  UNKNOWN,
  CLUBS,
  HEARTS,
}
...
Suit field = UNKNOWN;
...
{code}

And v2:

{code}
enum Suit {
  UNKNOWN,
  CLUBS,
  HEARTS,
  SPADES,
  DIAMONDS
}
...
Suit field = UNKNOWN;
...
{code}

Originally I though using something specific for the fallback, but thinking 
through all the use cases you always end up having with an enum with a 
"UNKNOWN" value which is always the right default value...

Aliases should be used for the same purpose as field aliases. (improving 
names...)



> 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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