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

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

    [ https://issues.apache.org/jira/browse/CASSANDRA-7066?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15033985#comment-15033985 ] 

Tomas Ramanauskas commented on CASSANDRA-7066:
----------------------------------------------

Hi, I created a new issue:
https://issues.apache.org/jira/browse/CASSANDRA-10788

This is a bit of code that is throwing java.lang.NullPointerException: null

https://github.com/apache/cassandra/blob/cc4d759c9023878760b0cbef854938cd302609d1/src/java/org/apache/cassandra/db/SystemKeyspace.java#L1341

{code}
/**
     * Check data directories for old files that can be removed when migrating from 2.1 or 2.2 to 3.0,
     * these checks can be removed in 4.0, see CASSANDRA-7066
     */
    public static void migrateDataDirs()
    {
        Iterable<String> dirs = Arrays.asList(DatabaseDescriptor.getAllDataFileLocations());
        for (String dataDir : dirs)
        {
            logger.trace("Checking directory {} for old files", dataDir);
            File dir = new File(dataDir);
            assert dir.exists() : dir + " should have been created by startup checks";

            for (File ksdir : dir.listFiles((d, n) -> d.isDirectory()))
            {
                for (File cfdir : ksdir.listFiles((d, n) -> d.isDirectory()))
                {
                    if (Descriptor.isLegacyFile(cfdir))
                    {
                        FileUtils.deleteRecursive(cfdir);
                    }
                    else
                    {
                        FileUtils.delete(cfdir.listFiles((d, n) -> Descriptor.isLegacyFile(new File(d, n))));
                    }
                }
            }
        }
    }
{code}

> Simplify (and unify) cleanup of compaction leftovers
> ----------------------------------------------------
>
>                 Key: CASSANDRA-7066
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7066
>             Project: Cassandra
>          Issue Type: Improvement
>            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.



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