Changing newid() to newsequentialid() on an existing table

Question

At the moment we have a number of tables that are using newid() on the primary key. This is causing large amounts of fragmentation. So I would like to change the column to use n

Answer 1

Thank you, yfeldblum! Your simple and concise explanation of COMB GUIDs really helped me out. I was actually looking at doing the reverse of this post: I had to get away from relying on newsequentialid() since I was trying to migrate a SQL Server 2012 db to Azure, and the newsequentialid() function is not supported there.

I was able to change all of my table PK defaults to COMB GUIDs, with the following syntax:

ALTER TABLE [dbo].[Company] 
ADD  CONSTRAINT [DF__Company__Company_ID__72E6D332]  
    DEFAULT (CONVERT([uniqueidentifier],CONVERT([binary](10),newid(),0)+CONVERT([binary](6),getdate(),0),0)) FOR [CompanyId]
GO

My SQL2012 db is now happily living in the Azure cloud.