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From "mck (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-9591) Scrub (recover) sstables even when -Index.db is missing
Date Fri, 12 Jun 2015 17:50:00 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-9591?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

mck updated CASSANDRA-9591:
---------------------------
    Attachment: 9591-2.0.txt

> Scrub (recover) sstables even when -Index.db is missing
> -------------------------------------------------------
>
>                 Key: CASSANDRA-9591
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9591
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: mck
>            Assignee: mck
>              Labels: sstablescrub
>             Fix For: 2.0.15
>
>         Attachments: 9591-2.0.txt
>
>
> Today SSTableReader needs at minimum 3 files to load an sstable:
>  - -Data.db
>  - -CompressionInfo.db 
>  - -Index.db
> But during the scrub process the -Index.db file isn't actually necessary, unless there's
corruption in the -Data.db and we want to be able to skip over corrupted rows. Given that
there is still a fair chance that there's nothing wrong with the -Data.db file and we're just
missing the -Index.db file this patch addresses that situation.
> So the following patch makes it possible for the StandaloneScrubber (sstablescrub) to
recover sstables despite missing -Index.db files.
> This can happen from a catastrophic incident where data directories have been lost and/or
corrupted, or wiped and the backup not healthy. I'm aware that normally one depends on replicas
or snapshots to avoid such situations, but such catastrophic incidents do occur in the wild.
> I have not tested this patch against normal c* operations and all the other (more critical)
ways SSTableReader is used. i'll happily do that and add the needed units tests if people
see merit in accepting the patch.
> Otherwise the patch can live with the issue, in-case anyone else needs it. I've uploaded
a cassandra distribution bundled with the patch as well to make life a little easier for anyone
finding themselves in such a bad situation.



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