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https://issues.apache.org/jira/browse/CASSANDRA-3399?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis updated CASSANDRA-3399:
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Attachment: 3399.txt
new patch w/ less crack smoking
> Truncate disregards running compactions when deleting sstables
> --------------------------------------------------------------
>
> Key: CASSANDRA-3399
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3399
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 0.7.0
> Reporter: Sylvain Lebresne
> Assignee: Jonathan Ellis
> Fix For: 0.8.8, 1.0.2
>
> Attachments: 3399.txt
>
>
> All truncation do is `cfs.markCompacted(truncatedSSTables)` without holding
> any lock or anything. Which have the effect of actually deleting sstables
> that may be compacting. More precisely there is three problems:
> # It removes those compacting sstables from the current set of active
> sstables for the cfs. But when they are done compacting,
> DataTracker.replaceCompactedSSTables() will be called and it assumes that the
> compacted sstable are parts of the current set of active sstables. In other
> words, we'll get an exception looking like the one of CASSANDRA-3306.
> # The result of the compaction will be added as a new active sstable
> (actually no, because the code will throw an exception before because of the
> preceding point, but that's something we should probably deal with).
> # Currently, compaction don't 'acquire references' on SSTR. That's because
> the code assumes we won't compact twice the same sstable and that compaction
> is the only mean to delete an sstable. With these two assumption, acquiring
> references is not necessary, but truncate break that first assumption.
> As for solution, I see two possibilities:
> # make the compaction lock be per-cf instead of global (which I think is easy
> and a good idea anyway) and grab the write lock to do the markCompacted call.
> The big downside is that truncation will potentially take much longer.
> # had two phases: mark the sstable that are not compacting as compacted and
> set the dataTracker as 'truncated at', and let it deal with the other sstable
> when their compaction is done. A bit like what is proposed for CASSANDRA-3116
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