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Re: identity columns

From: David Cressey <david_at_dcressey.com>
Date: Fri, 11 Jan 2002 17:05:51 GMT
Message-ID: <PXE%7.118$Nq6.5149@petpeeve.ziplink.net>


I made a mistake in my previous reply. When you audit the invoices, looking for gaps, it is NOT necessary to view the invoices as a sequence rather than a set. I said the opposite in my last reply. Sorry.

You can, in fact, see them as a set. What you do have to see as a sequence is the act of issuing invoices. That's where the invoice number comes from. The invoice number itself is a sequence, not just a set.

Something parallel goes on when you audit a DBMS to make sure all the transactions have been applied to it. If each transaction is tagged with something called a "transaction sequence number" or some such phrase, it can be of interest to ensure that no transactions end up missing and unaccounted for, that there are no "gaps". Given that some transactions end in rollbacks, this needs to be accounted for, as well.

--
Regards,
    David Cressey
    www.dcressey.com
Received on Fri Jan 11 2002 - 11:05:51 CST

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