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From "Jun Rao (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-34) Hinted handoff rows never get deleted
Date Tue, 05 May 2009 00:01:31 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-34?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12705833#action_12705833
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Jun Rao commented on CASSANDRA-34:
----------------------------------

Looked at the new patch. Here are some comments.

1. Move the comments above sendMessage to the beginning of class.

2. There is compilation error in MinorCompactionManager because of the removed HintedHandOff
class.

3. Your new code deletes a column using the same timestamp as the column to be deleted. This
is a more fundamental question. If a column has a non-delete entry and a deleted entry with
the same timestamp, which one wins? I don't think that we can rely on the ordering of the
insertion/deletion. This is because the insertion and the deletion can end up in different
SSTables. During compaction, FileStruct is sorted only by keys. Therefore, columns from different
SSTables with the same key can come in arbitrary order. One solution is to modify CF.addColumn
such that a deletion always wins when the column timestamp is the same. Not sure if there
is any other implications, though.


> Hinted handoff rows never get deleted
> -------------------------------------
>
>                 Key: CASSANDRA-34
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-34
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Jonathan Ellis
>             Fix For: 0.3
>
>         Attachments: 0001-cleanup.patch, 0002-fix-HHM.patch, issue34.patch_v1, issue34.patch_v2
>
>
> from the list: "after the hints are delivered, the hinted keys are deleted from the hinted
CF only, but not from the application CF."
> Prashant verified that this is a bug that can't be fixed until deletes are fully working.
> Note: when we fix this, see if we can do so w/o compromising the immediate-GC of the
hinted CF keys.

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