[AccessD] UnDelete

MartyConnelly martyconnelly at shaw.ca
Tue Jan 13 16:27:07 CST 2004


Here is Peter Millers explantion from pksolutions.com

In general, its not possible to recover more than a very small
percentage of deleted records when the records are deleted but the
table is not.  This has been true for all recent versions of Access.

The reason for this is that Access/Jet copy the first deleted record
over the remaining deleted records on a data page, so even though the
file does not decrease in size, most of the data (usually >95% of it)
is still completely overwritten.  If there is doubt about this, I
encourage anyone with questions to make a copy of a database they use
frequently, open the copy, delete all the data from a key table
(noting some of the record values), then close the copy and open it in
a hex editor.  Most of the file contents will appear garbled, but
scroll through until you find data from the table you deleted records
from.  You will see numerous copies of a few of the deleted records.
Can these records be recovered?  Yes, but when you see, say 20 copies
of the same deleted record, while all twenty copies can be recovered,
there should have been twenty distinct records and not twenty copies
of the same record.  In other words, 19 of the deleted records have
been overwriten.

I would strongly advise Ronley and anyone else reading this thread to
not trust someone like Marcus who lies about this.  If there is any
doubt, and you don't mind sending your file in to someone like Marcus,
and you'll soon find out that he can't in fact do what he claims.
Only a small number of distinct deleted records can be recovered.  Its
not a question of skill - its a question of whether or not all the
deleted records exist to be recovered in any state at all, and
unfortunately, they do not.

This is not an issue if the entire table was deleted (ie, not the
records alone, but the table definition itself).  Any and all deleted
tables can always be recovered, but deleted records from within a
table that is itself not deleted are not recoverable in any meaningful
sense.

Peter Miller
PK Solutions
_____________________________________________________

Jim Dettman wrote:

>Julie,
>
>  yes they are there, but there is no functionality in Access/JET to
>undelete them.  Part of the reason is the LV (Long Value Pages) are recycled
>(depending on a registry setting), so it may not always be possible to bring
>a record back if records have been saved.
>
>  Because of that, an undelete has never been built into Access.
>
>Jim Dettman
>President,
>Online Computer Services of WNY, Inc.
>(315) 699-3443
>jimdettman at earthlink.net
>
>-----Original Message-----
>From: accessd-bounces at databaseadvisors.com
>[mailto:accessd-bounces at databaseadvisors.com]On Behalf Of Julie
>Reardon-Taylor
>Sent: Tuesday, January 13, 2004 3:45 PM
>To: accessd at databaseadvisors.com
>Subject: Re: [AccessD] UnDelete
>
>
>Aren't Access records marked for deletion, and not actually deleted until
>the database is compacted?  Shouldn't these records still be in the table?
>Can't I unmark these records for deletion?
>
>
>
>Julie Reardon-Taylor
>PRO-SOFT OF NY, INC.
>www.pro-soft.net
>
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>  
>

-- 
Marty Connelly
Victoria, B.C.
Canada





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