UUID Generation Still v4 Instead of v7 After Upgrading to .NET 9 / EF Core 9

[adnan-kamili]

After upgrading to .NET 9 and EF Core 9, I noticed that the UUIDs generated for primary keys are still v4 instead of the expected version v7.

Here’s the entity class where the UUIDs are generated:

[Index(nameof(CreatedAt))]
public abstract class BaseEntity : IEntity
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public string Id { get; set; }

    public DateTime CreatedAt { get; set; }

    public DateTime UpdatedAt { get; set; }
}

[roji]

Thanks, confirmed - this is because you're using a string Id instead of a Guid Id; if you switch to Guid (which is recommended and more efficient anyway), you should see UUIDv7 getting generated. But I'll fix this for strings as well.

Note: the same issue exists for SQL Server, opened dotnet/efcore#35639

[adnan-kamili]

@roji Thanks for the quick fix.

Unfortunately, we initially used string instead of GUID for the primary key. Not sure if there’s an easy way to update the primary key type from string to UUID in place while minimizing downtime.