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From "Mike Matrigali (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5273) enhance SYSCS_CHECK_TABLE to check every page in the database
Date Fri, 10 Jun 2011 21:41:58 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5273?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mike Matrigali updated DERBY-5273:
----------------------------------

    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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