Support for newsequentialid()
To avoid fragmentation for clustered indexes, the newsequentialid() function should be suported for uniqueidentifier primary key columns as a default value.
Fernando Correia commented
It doesn't have to be perfectly identical to the SQL Server implementation. For instance, it could be implemented as the popular "COMB GUID" strategy, combining the current date/time with a random number. The important thing is that it is roughly sequential instead of all over the place like full random GUIDs.