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Posted to dev@avro.apache.org by "Doug Cutting (Commented) (JIRA)" <ji...@apache.org> on 2012/01/13 19:54:39 UTC
[jira] [Commented] (AVRO-991) Allow combining multiple Avro files
within a stream. (no files on disk)
[ 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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