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https://issues.apache.org/jira/browse/AVRO-251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12790333#action_12790333
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Doug Cutting commented on AVRO-251:
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> I think the usecase for it (I know you have one in mind, and we're hinting at
> it in this JIRA)
I think you're referring to AVRO-160. That's indeed what instigated this last
week, but over the weekend I've since had second thoughts about actually using
it there. I still believe this is useful for some applications, but, if folks
agree with me about AVRO-160, then committing this is not urgent.
> one alternative is to ditch the whole binary representation and store the
> original schema in Avro-encoded binary JSON.
I like that idea. It'd be bigger than with the schema here, since all of the
Avro keywords will be included, but it will still be considerably smaller and
faster than textual JSON. Plus the specification for JSON is much less likely
to change, so its schema is likely to be much more stable and hence its less
risky to assume that schema as a system constant.
> I think you would agree that using either the specific (my preference) API or
> the generic API would be clearer from a code perspective.
Perhaps a bit, but not much. It adds an intermediate representation, which has
some cognitive overhead, which this code does not. This code instead requires
some understanding of Avro's encoder/decoder API. I don't think that would
reduce the code size by more than perhaps 10%, and I don't think it would be
much more robust. Efficiently mapping the union branch classes to Schema
subclasses would require something like a Map<Class,Schema.Type>. This table
could be built by processing the schema, rather than as this patch does by
assuming that the Schema.Type enum is sync'd with the union. But we could
change this patch to build that mapping from the schema too if we are
particularly concerned about that.
I actually generated the specific code first, and considered writing it that
way, but it felt like more work to me.
> add schema for schemas
> ----------------------
>
> Key: AVRO-251
> URL: https://issues.apache.org/jira/browse/AVRO-251
> Project: Avro
> Issue Type: New Feature
> Components: java
> Reporter: Doug Cutting
> Assignee: Doug Cutting
> Fix For: 1.3.0
>
> Attachments: AVRO-251.patch, AVRO-251.patch
>
>
> A schema for schemas would permits schemas to be written in binary.
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