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Posted to derby-dev@db.apache.org by "Mike Matrigali (JIRA)" <ji...@apache.org> on 2011/06/10 23:41:58 UTC
[jira] [Updated] (DERBY-5273) enhance SYSCS_CHECK_TABLE to check
every page in the database
[ https://issues.apache.org/jira/browse/DERBY-5273?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Mike Matrigali updated DERBY-5273:
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Issue & fix info: [Newcomer]
I am marking this newcomer. Might be good as a second project working on Derby. Good for someone who wants to learn a bit
about the underlying storage structure. Most of the work is figuring out what backup does and then work out a way to something
similar from a call to the consistency checker. Probably means adding a new raw store interface that can be called from
the consistency checker procedure similar to how backup is called.
> enhance SYSCS_CHECK_TABLE to check every page in the database
> -------------------------------------------------------------
>
> Key: DERBY-5273
> URL: https://issues.apache.org/jira/browse/DERBY-5273
> Project: Derby
> Issue Type: Improvement
> Affects Versions: 10.8.1.2
> Reporter: Mike Matrigali
>
> The current consistency checker operates at a logical layer. It checks that indexes and base user tables are consistent. In doing so
> it checks most of the pages in the database, but not all. I don't think it checks blob/clob chains. I know it does not check free pages.
> One simple enhancement would be to just read every page of every file in the database into the cache. This would at least check that
> all pages were valid. I believe code to do this can either be copied or shared with the backup code which at a low level reads each page
> from disk into cache and then writes it to the backup directory.
> DERBY-5266 looks like a case where the consistency checker missed an invalid page that backup is subsequently finding. It would
> be great if anyone has an example of a database that they can post that has a similar problem so that we can test a real live problem,
> rather than making one up.
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