Posted by Martijn Tonies on 11/03/05 09:51

> > I've never written any extended procedures, so perhaps you could
> > explain why this would give awful performance?
> >
> > I imagine the call could be as:
> >
> > select ...
> > from ...
> > where myregexp_match(mycolumn, myexpression, myvalue)
>
> That's not really how you call extended stored procedure. But you could
> encapsulate the XP in a user-defined function to get this syntax. However,
> there is a big overhead for calling a UDF in a WHERE clause in SQL 2000
> (this overhead has been reduced in SQL 2005). If you then add a call to
> extended stored procedure that gives you context switches and all, it's
> getting really bad.

Then when are XPs actually useful?

> Then add to this that if you have a bug in your XP that causes an
> access violation or similar, it's not only the XP that crashes. You
> blow away the entire SQL Server.

I understand this part, seems to be the case with pretty much all
extending to DB engines (unless managed or Java or whatever).

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