[
https://issues.apache.org/jira/browse/AVRO-1340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16143160#comment-16143160
]
Felix GV commented on AVRO-1340:
--------------------------------
I am not convinced that it should be compatible to change "fallbackSymbol".
Let's take a more realistic example than cards to illustrate the point.
V1:
"name":"httpResponseCode",
"symbols":["UNKNOWN", "200", "404", "500"],
"fallbackSymbol": "UNKNOWN"
V2:
// same, except:
"fallbackSymbol":"500"
This is a significant semantic difference in the data definition. I used to be
able to throw new HTTP codes into the enum and expect that non-upgraded
consumers had to implement a sensible unknown strategy for them. But then in
V2, I am changing the contract so that it will treat any unknown codes as 500s
(internal server errors). A redirect (30x) is a non-error code, and I don't
want it to be assumed to be an error.
Of course, this is use case-dependent. There could be cases where changing the
fall-back is sensible. But I think it could lead to confusing behavior in other
cases...
> 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.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
