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https://issues.apache.org/jira/browse/AVRO-695?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14030889#comment-14030889
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Doug Cutting commented on AVRO-695:
-----------------------------------
This does not appear to write data that other implementations can read. Am I
missing something? It also appears to require that, to support circularity,
the first field in a record must be a string.
Rather, I think we must explicitly add the reference to the schema, e.g.:
{code}
{"type":"record", "name":"CircularListOfStrings", "fields":[
{"name":"value", "type":"string"},
{"name":"next", "type":["CircularListOfStrings","int"]}
]}
{code}
A circular instance would appear to existing Avro implementations as a
non-circular list of strings terminating with an integer.
> Cycle Reference Support
> -----------------------
>
> Key: AVRO-695
> URL: https://issues.apache.org/jira/browse/AVRO-695
> Project: Avro
> Issue Type: New Feature
> Components: spec
> Affects Versions: 1.7.6
> Reporter: Moustapha Cherri
> Attachments: avro-1.4.1-cycle.patch.gz, avro-1.4.1-cycle.patch.gz,
> avro_circular_references.zip
>
> Original Estimate: 672h
> Remaining Estimate: 672h
>
> This is a proposed implementation to add cycle reference support to Avro. It
> basically introduce a new type named Cycle. Cycles contains a string
> representing the path to the other reference.
> For example if we have an object of type Message that have a member named
> previous with type Message too. If we have have this hierarchy:
> message
> previous : message2
> message2
> previous : message2
> When serializing the cycle path for "message2.previous" will be "previous".
> The implementation depend on ANTLR to evaluate those cycle at read time to
> resolve them. I used ANTLR 3.2. This dependency is not mandated; I just used
> ANTLR to speed thing up. I kept in this implementation the generated code
> from ANTLR though this should not be the case as this should be generated
> during the build. I only updated the Java code.
> I did not make full unit testing but you can find "avrotest.Main" class that
> can be used a preliminary test.
> Please do not hesitate to contact me for further clarification if this seems
> interresting.
> Best regards,
> Moustapha Cherri
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