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From "Stefania (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-7066) Simplify (and unify) cleanup of compaction leftovers
Date Mon, 04 May 2015 08:04:06 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7066?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14526389#comment-14526389
] 

Stefania commented on CASSANDRA-7066:
-------------------------------------

Thanks for your feedback, [~benedict], [~JoshuaMcKenzie], [~krummas].

I've removed temporary files and descriptor types entirely with a small exception for rewriting
metadata which still uses a temporary file. I also plan on implementing the standalone tool
suggested by Marcus.

[~benedict]: assuming you want to be the reviewer, you can start with a quick first round
if you have some spare time (https://github.com/stef1927/cassandra/commits/7066-8984-alt).
I am still testing (some dtests are broken) and reviewing myself but you may want to take
a look at the transaction log class, which is called *OperationLog*. I am not entirely sure
if the integration of this class with the SSTableRewriter and SSTableWriter is what you had
in mind or if it should be more tightly integrated.




> 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
>
>
> 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or conversely not cleanup files that have been superceded); and 2) it's only used for a regular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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