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https://issues.apache.org/jira/browse/AVRO-2148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16372187#comment-16372187
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Ashok commented on AVRO-2148:
-----------------------------
FYI, Hive avro deserializer is being used to read the Avro data files and that
requires to be associated with a schema. Without being able to evolve the
schema, parsing the data of multiple versions will get difficult and hence the
need to allow the above
> Avro: Schema compatibility/evolution - attribute size change
> ------------------------------------------------------------
>
> Key: AVRO-2148
> URL: https://issues.apache.org/jira/browse/AVRO-2148
> Project: Avro
> Issue Type: Improvement
> Components: java
> Affects Versions: 1.8.2
> Reporter: Ashok
> Priority: Critical
>
> Let's assume the schema changed from V1 to V2. Currently, we can't create a
> merge of the two schema that makes it a compatible for both. Depending on
> what size we keep in the reader schema (the merged schema), you can only read
> avro files of schema V1 or V2, not both. If we keep the higher attribute
> size value (64), it should allow the read of avro files with lower attribute
> size value (16)
>
> * *V1 schema:*
> { "name": "sid", "type": [ "null",
> { "type": "fixed", "name": "SID", "namespace": "com.int.datatype", "doc": "",
> "size": *64* }
> ], "doc": "", "default": null, "businessLogic": "" }
>
> * *V2 schema:*
> { "name": "sid", "type": [ "null",
> { "type": "fixed", "name": "SID", "namespace": "com.int.datatype", "doc": "",
> "size": *16* }
> ], "doc": "", "default": null, "businessLogic": "" }
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