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https://issues.apache.org/jira/browse/CASSANDRA-7066?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14578818#comment-14578818
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Stefania commented on CASSANDRA-7066:
-------------------------------------
Thank you for your review Benedict. I should be able to resume this in a couple
of days.
Regarding SSTableDeletingTask, I'll see if I can remove it.
bq. Why does SSTableWriter.finish() take a TxnLog? For convenience/clarity?
Perhaps we should have a wrapped SSTableWriter that encapsulates this, so we
don't confuse matters when we have another encapsulation (Rewriter, etc)?
Pure convenience. I'll introduce a wrapper.
bq. I wonder if it might be more robust to only log the descriptors (except the
opposing log file, which would be a slight special case, but acceptable since
it would be logged first, so easily disambiguated). Just seems like we may be
less likely to have some mistake that leaves components lying around that we
should have cleaned up.
The current strategy is to log any file that we might create, whether it exists
or not, and to delete files only if they exist. Logging a descriptor would
therefore be equivalent, save space in the log, and add clarity. We also need
to know the relative path, because a transactions folder may be in a location
that is not a child of the data folder. I've seen it happen in some unit tests.
But I think we could just log the relative path and the descriptor base name
and that should be fine.
> Simplify (and unify) cleanup of compaction leftovers
> ----------------------------------------------------
>
> Key: CASSANDRA-7066
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7066
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Assignee: Stefania
> Priority: Minor
> Labels: compaction
> Fix For: 3.x
>
> Attachments: 7066.txt
>
>
> Currently we manage a list of in-progress compactions in a system table,
> which we use to cleanup incomplete compactions when we're done. The problem
> with this is that 1) it's a bit clunky (and leaves us in positions where we
> can unnecessarily cleanup completed files, or conversely not cleanup files
> that have been superceded); and 2) it's only used for a regular compaction -
> no other compaction types are guarded in the same way, so can result in
> duplication if we fail before deleting the replacements.
> I'd like to see each sstable store in its metadata its direct ancestors, and
> on startup we simply delete any sstables that occur in the union of all
> ancestor sets. This way as soon as we finish writing we're capable of
> cleaning up any leftovers, so we never get duplication. It's also much easier
> to reason about.
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