[jira] [Reopened] (CASSANDRA-7066) Simplify (and unify) cleanup of compaction leftovers

["Benedict (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-7066?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benedict reopened CASSANDRA-7066:
---------------------------------

[~stefania]: I'm not sure if we entirely settled on a modification, but it sounds like we should revisit this a little, so I'm reopening.

It would be best if this system get finalised prior to the beta, and if possible the alpha, so we should probably focus on this ahead of other tickets.

I think the proposed changes should deal with any of the outlined concerns, however I think they can be made even more robust to backup interplay: if we also log the last modified time of the file we're deleting alongside it, then we can bail out if any of these mismatch for _any_ file, and we can log some panics. This should all make us very paranoid and prefer retention of data, as well as make us a little more robust to filesystem failures and perhaps also bugs of our own making. Although we will never be truly shielded from any of these issues.

> 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: benedict-to-commit, compaction
>             Fix For: 3.0 alpha 1
>
>         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us in positions where we can unnecessarily cleanup completed files, or conversely not cleanup files that have been superceded); and 2) it's only used for a regular compaction - no other compaction types are guarded in the same way, so can result in duplication if we fail before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.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)