How to persist a calculated GEOMETRY or GEOGRAPHY column

I'm trying to create a table under SQL Server 2008 containing a GEOMETRY column and a calculated variation thereof.

Considering the following table where the calculated column returns a buffered geometry:

CREATE TABLE [dbo].[Test] (
    [Geometry]  GEOMETRY NOT NULL,
    [Buffer]  FLOAT  NOT NULL,
    [BufferedGeometry] AS ([Geometry].STBuffer([Buffer])) PERSISTED
);

The problem with this is it results in the following error:

Msg 4994, Level 16, State 1, Line 2 Computed column 'BufferedGeometry' in table 'Test' cannot be persisted because the column type, 'geometry', is a non-byte-ordered CLR type.

I have search BOL and the web and can't seem to find a solution to my problem. I really would like it to be persisted so I can index it effectively. I could set it in code, but then I have the possibility of inconsistent data as I require both values at some point in time.

Anyone played with this and know a solution or workaround?

From stackoverflow Craig Nicholson

• I guess you could use a trigger to calculate it and store it to the [BufferedGeometry] field

  Craig Nicholson : Personally I don't like using triggers in databases, I haven't needed to use one now for many years and I hopefully won't need to resort to one.

  DJ : I agree - but sometimes it is the only way to go :-)
  From DJ