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https://issues.apache.org/jira/browse/AVRO-2689?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17018031#comment-17018031
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Ryan Skraba commented on AVRO-2689:
-----------------------------------
To check evolution with {{tojson}}, we'd probably want to specify the reader
schema in the GenericDatumReader created here:
[https://github.com/apache/avro/blob/master/lang/java/tools/src/main/java/org/apache/avro/tool/DataFileReadTool.java#L75]
The writer schema is automatically set when the DataFileStream is created. If
we want to set a different reader schema (than the one found in the file), it
should be set by calling
{code:java}
reader.setExpected(readerSchema){code}
just after the DataFileStream is created.
> Avro-tools should have a way to test schema evolution.
> ------------------------------------------------------
>
> Key: AVRO-2689
> URL: https://issues.apache.org/jira/browse/AVRO-2689
> Project: Apache Avro
> Issue Type: Improvement
> Components: java
> Reporter: Ryan Skraba
> Priority: Major
>
> The avro-tools command line should have at least one way to test
> reading/writing with an evolved schema. This would be useful for testing
> schema evolution and reproducing errors or bug reports from the command line.
> A good candidate would be to add a {{--reader-schema}} option to the
> {{tojson}} tool (where the writer schema comes from the data file).
> Alternatively, the {{fragtojson}} already takes the writer schema and we
> could add {{--reader-schema-file}}.
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