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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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