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https://issues.apache.org/jira/browse/AVRO-1340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16664289#comment-16664289
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ASF GitHub Bot commented on AVRO-1340:
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cutting commented on a change in pull request #357: Updated spec to agree with
implementation of AVRO-1340
URL: https://github.com/apache/avro/pull/357#discussion_r228334530
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File path: doc/src/content/xdocs/spec.xml
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@@ -172,6 +172,13 @@
be unique; duplicates are prohibited. Every symbol must
match the regular expression <code>[A-Za-z_][A-Za-z0-9_]*</code>
(the same requirement as for <a href="#names">names</a>).</li>
+ <li><code>default:</code> A default value for this
+ enumeration, used during resolution when the reader
+ encounters a symbol from the writer that isn't defined
+ in the reader's schema. See documentation for record
Review comment:
Are you referring to the Java documentation here? Probably best not to.
Rather we can say that the default symbol must be present in the enum.
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> 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
> Assignee: Adam Bellemare
> Priority: Minor
> Fix For: 1.9.0
>
>
> 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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