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From Mike Matrigali <mikem_...@sbcglobal.net>
Subject Re: Secure Delete
Date Tue, 16 Oct 2007 20:53:57 GMT
Ruben Misrahi wrote:
> We want to get "security-certified" and we need to know if deleting a 
> record in Derby actually eliminates or physically overrides that space 
> and/or if there is a way to do that.
> And more specifically, if I have a 200 byte field and I override it with 
> a 2 character field. Can some still get the data that was there?
you ask about deleting, but your example is an update.  Do you care 
about just updating, or both?  Also is your question what happens after
the delete/update operation commits or after the statement but possibly
before the commit.

Once any operation happens there is no way through derby interfaces to 
get the old value.  If you are concerned about bits/bytes left on pages
that is a different story.  For instance in the case of delete of a 
record when statement happens lock is granted on row, row is marked 
deleted but data left on page, and finally after commit the bytes are
available for reuse sometime in the future but are not guaranteed to
be overwritten/reused.

Updates are more complicated depending on whether after update the row
is bigger or smaller and if there was any internal reserved space 
associated with the row.  Again different stuff happens before commit
and after.

> We're willing to pay for an answer. Please email to:
> rnmisrahi@ameritech.net <mailto:rnmisrahi@ameritech.net>
> Thanks
> -- 
> Ruben Misrahi

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