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From "Josh Spiegel (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AVRO-1262) Provide access to the writer schema from the mapper
Date Fri, 01 Mar 2013 23:47:12 GMT

    [ https://issues.apache.org/jira/browse/AVRO-1262?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13591104#comment-13591104
] 

Josh Spiegel commented on AVRO-1262:
------------------------------------

Thanks!  It looks like you exposed the writer schema on the RecordReader.  Is the RecordReader
accessible from the Mapper?  I can see that the RecordReader is referenced in the MapContext
(*.hadoop.mapreduce.MapContext) but access to it seems to be private.  Am I missing something?

                
> 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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