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From "Doug Cutting (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AVRO-991) Allow combining multiple Avro files within a stream. (no files on disk)
Date Fri, 13 Jan 2012 18:54:39 GMT

    [ https://issues.apache.org/jira/browse/AVRO-991?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13185746#comment-13185746
] 

Doug Cutting commented on AVRO-991:
-----------------------------------

I think this would work.  We'd need to be able to distinguish the start of a block from the
start of the next file.  A block starts with the count of items in it, encoded as a variable-length
zig-zag-encoded long.  A file starts with ASCII 'O'.  Interpreted as a variable-length zig-zag
encoded long, this is -40, which is an invalid item count.  So a DataFileStream would need
to, when the item count is -40, try to read a file header, and if its schema is compatible,
update its sync and codec and keep reading.

                
> Allow combining multiple Avro files within a stream. (no files on disk)
> -----------------------------------------------------------------------
>
>                 Key: AVRO-991
>                 URL: https://issues.apache.org/jira/browse/AVRO-991
>             Project: Avro
>          Issue Type: Improvement
>          Components: java
>    Affects Versions: 1.6.1
>            Reporter: Frank Grimes
>
> It would be nice to be able to do as follows:
>   cat file1.avro file2.avro | java -jar avro-tools.jar streamcombine > combined-file.avro
> or similarly
>   
>   hadoop dfs -cat hdfs://hadoop/file1.avro hdfs://hadoop/file2.avro | java -jar avro-tools.jar
streamcombine | hdfs -put - hdfs://hadoop/combined-file.avro
> See the following thread for details: http://mail-archives.apache.org/mod_mbox/avro-user/201201.mbox/%3cC08F1DE9-97A8-4D28-B0AD-5E4A7F32F028@gmail.com%3e

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