Sequential GUID in Linq-to-Sql?

Question

I just read a blog post about NHibernate\'s ability to create a GUID from the system time (Guid.Comb), thus avoiding a good amount of database fragmentation. You could call

Answer 1

You can always call UuidCreateSequential; this is the 'old' guid generator (pre-2000-ish when MSFT changed it to the more random style guids we are used to today). They renamed the old UuidCreate to UuidCreateSequential, and put their new guid generator in a new implementation of UuidCreate. UuidCreateSequential is also what SQL Server uses in NewSequentialID(), and it is as unique as normal guids but with the benefit that they are sequential if you create a pile of them in a row in the same process.

using System;
using System.Runtime.InteropServices;

namespace System
{
    public static class GuidEx
    {
        [DllImport("rpcrt4.dll", SetLastError = true)]
        private static extern int UuidCreateSequential(out Guid guid);
        private const int RPC_S_OK = 0;

        /// 

        /// Generate a new sequential GUID. If UuidCreateSequential fails, it will fall back on standard random guids.
        /// 
        /// A GUID
        public static Guid NewSeqGuid()
        {
            Guid sequentialGuid;
            int hResult = UuidCreateSequential(out sequentialGuid);
            if (hResult == RPC_S_OK)
            {
                return sequentialGuid;
            }
            else
            {
                //couldn't create sequential guid, fall back on random guid
                return Guid.NewGuid();
            }
        }
    }
}