How to comb non Identity Guid

[mwpowellhtx]

Hello,

I've got an Attachments table I am dealing with. Originally the data was table-bound VARBINARY(MAX), and the row ids were (are) BIGINT, etc.

The domain model, and related views and view models, are also, inexplicably, strongly coupled with the BIGINT (or C# long) Id property. There's enough there that I really don't want to muck with the Id one way or another if I can avoid it.

We are wanting to migrate the binary data from table to FILESTREAM, via SQL Server 2008 R2 and its features. So the data portion is easy enough. What we also need is the ROWGUIDCOL column added. In and of itself, no problem.

Except in the domain model mapping through the NHibernate ORM. How do we help the Guid column comb, while also not mucking with the Id? Is CompositeId an option with this sort of thing, but I didn't see anything in particular jump out at me there, either?

Any ideas? Thank you...

Best regards,

Michael

[mwpowellhtx]

After doing a tiny bit of research, the following approach came to mind.

On the database side, we can make the assumption today SQL Server 2008 R2, and use the NEWSEQUENTIALID() strategy to help with fragmentation.

On the domain model side of things, the Id, will leave alone. It is still a long, mapped to BIGINT, etc. The Guid column, I suppose can be mapped to:

Map(x => x.DataGuid).Generated.Always();

And if I understand how VARBINARY FILESTREAM data works, the Guid is fine generated like that. The rest is handled through whether the corresponding Data mapping IS NULL, etc, along these lines.

Plausible? Short of some way to marry the two in a composite, which I'd like to avoid anyway, this seems like the best possible solution.

Thank you...

 

Best regards,

Michael

[Oskar Berggren]

I'm not quite sure what's going on, but yeah if you just want to have the db-generated GUID available in the model, "Generated" seems like a reasonable idea.

/Oskar

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[Michael Powell]

On Sun, Oct 12, 2014 at 7:10 AM, Oskar Berggren
<oskar.b...@gmail.com> wrote:
> I'm not quite sure what's going on, but yeah if you just want to have the
> db-generated GUID available in the model, "Generated" seems like a
> reasonable idea.

Well, the crux of it is, I can't simply swap a Guid for a long, even
though technically that's what it should be with FILESTREAM,
ROWGUIDCOL, etc. At least, not without more of a retrofit on the
domain model extend outwards into the user interface views, bindings,
etc, than I am wanting to pursue with this effort.

Generated it is.

Thank you for the second opinion.

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