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https://issues.apache.org/jira/browse/AVRO-1262?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13618419#comment-13618419
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Harsh J commented on AVRO-1262:
-------------------------------
Josh,
You're correct. One does not get access to the RR via a Mapper in new API, but
can get it if they use the old API's
[MapRunner|http://hadoop.apache.org/docs/current/api/org/apache/hadoop/mapred/MapRunner.html#run(org.apache.hadoop.mapred.RecordReader,%20org.apache.hadoop.mapred.OutputCollector,%20org.apache.hadoop.mapred.Reporter)]
implementation.
I guess one other way would be to have the RR load a defined config key during
its initialization, which can be fetched from the Mapper. This would be more
"inelegant" (i.e. no API) but would work with both APIs.
> Provide access to the writer schema from the mapper
> ---------------------------------------------------
>
> Key: AVRO-1262
> URL: https://issues.apache.org/jira/browse/AVRO-1262
> Project: Avro
> Issue Type: New Feature
> Components: java
> Affects Versions: 1.7.4
> Reporter: Josh Spiegel
> Assignee: Doug Cutting
> Fix For: 1.7.5
>
> Attachments: AVRO-1262.patch
>
>
> When using an Avro InputFormat like AvroKeyInputFormat, the writer schema of
> the container file should be accessible from the mapper. This is useful in
> cases where a reader schema is not specified.
> A workaround is to use FileSplit#getPath() to access the container file and
> manually pull out the schema. This workaround is not ideal because
> internally the writer schema has already been read (see
> AvroRecordReaderBase#createAvroFileReader(...)) - it is awkward and
> inefficient for the user to repeat this work.
> See also:
> http://mail-archives.apache.org/mod_mbox/avro-user/201302.mbox/%3CCAOF3b61nFw4ztOo9Q5pHHtoUDFZ3sRrvEdRGbXGV_cscTqd5LA%40mail.gmail.com%3E
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