That is very true - and since I have no control over the hardware, it is entirely reasonable that some systems will have no MAC. I will just have to make a testcase and work with it.

----- Original Message -----
From: Daniel Rail
To: firebird-support@yahoogroups.com
Sent: Tuesday, May 25, 2004 5:23 AM
Subject: Re: [firebird-support] Re: Primary Keys - [was] Database File Size


Hi,

At May 24, 2004, 20:18, David Johnson wrote:

> The GUID is attractive to me in this case because, like the
> integer keys, it eliminates the issue of control of the environment
> and business structures from my database schema. Unlike the integer
> keys, it does not require any centralized coordination or alteration
> of records in transit.

Be careful in your assumptions that GUIDs will always be unique,
across computers. The generation of GUIDs is based on the MAC address
of a network card. If the computer doesn't have a network card(i.e.:
standalone computer with dial-up internet access, and no network card
installed), then the GUIDs will be guaranteed to be unique locally on
that computer, but NOT with other computers. And, given this scenario,
you might end up having duplicate GUIDs in your PKs. So, you still
have to make conflict resolution when transferring between databases.
Unless, you can be assured at 100% that that scenario will never
happen.

--
Best regards,
Daniel Rail
Senior System Engineer
ACCRA Group Inc. (www.accra.ca)
ACCRA Med Software Inc. (www.filopto.com)


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