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https://issues.apache.org/jira/browse/HDFS-10460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15342175#comment-15342175
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Kai Zheng commented on HDFS-10460:
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bq. can continue setting block.setNumBytes(getRemaining()); logic in Replicated
and Striped block. Then will consider reconstruction as a special case and will
create reconBlockGroup object with actualNumBytes, like I'm doing in the
current patch.
Yeah I understand your opinion. I thought both approaches should work because
they're essentially the same. You're looking at this from another perspective
and want this to be consistent with replicated block. It sounds good. On the
other hand, checksum for striping block group is a newly added function and
protocol, and in this, we need to pass the exact block group object to datanode
side for reconstruction need, as we did for erasure coding worker, and to do
the checksuming in datanode side, we also need to pass the requestedLength.
Doing this would look the related codes and protocol look more naturable and
readable. IMO, {{requestedLength}} would be better understandable than
{{actualNumBytes}}, and for the latter, you would have to explain about it, and
you also need to setNumBytes back and forth against the block group object.
> Erasure Coding: Recompute block checksum for a particular range less than
> file size on the fly by reconstructing missed block
> -----------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-10460
> URL: https://issues.apache.org/jira/browse/HDFS-10460
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode
> Reporter: Rakesh R
> Assignee: Rakesh R
> Attachments: HDFS-10460-00.patch, HDFS-10460-01.patch
>
>
> This jira is HDFS-9833 follow-on task to address reconstructing block and
> then recalculating block checksum for a particular range query.
> For example,
> {code}
> // create a file 'stripedFile1' with fileSize = cellSize * numDataBlocks =
> 65536 * 6 = 393216
> FileChecksum stripedFileChecksum = getFileChecksum(stripedFile1, 10, true);
> {code}
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