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Zhanwei.Wang commented on HDFS-3107: ------------------------------------ Add more detail to my previous question, how to define "may read content of a file that will be truncated", that is the "visibility" problem. If a file is opened and read just before truncation, should the truncated data be visible? Or just depends on the process of truncation? What if a file is opened before truncation and read after truncation? > HDFS truncate > ------------- > > Key: HDFS-3107 > URL: https://issues.apache.org/jira/browse/HDFS-3107 > Project: Hadoop HDFS > Issue Type: New Feature > Components: data-node, name-node > Reporter: Lei Chang > Attachments: HDFS_truncate_semantics_Mar15.pdf, > HDFS_truncate_semantics_Mar21.pdf > > Original Estimate: 1,344h > Remaining Estimate: 1,344h > > Systems with transaction support often need to undo changes made to the > underlying storage when a transaction is aborted. Currently HDFS does not > support truncate (a standard Posix operation) which is a reverse operation of > append, which makes upper layer applications use ugly workarounds (such as > keeping track of the discarded byte range per file in a separate metadata > store, and periodically running a vacuum process to rewrite compacted files) > to overcome this limitation of HDFS. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira