hostory tables with a generic function?

Hi,

I'm looking at the logging aof a database we'll put in production soon.
I've seen some posts on this list about history tables, like mentioned in
http://www-106.ibm.com/developerworks/web/library/wa-dbdsgn2.html .
I think I'll go that way too, but I still have some questions on the approach:

- is it possible to write only one function used for all logging triggers?
As illustrated in http://www.varlena.com/varlena/GeneralBits/57.php , it is possible to use
one function for tracking last update times for all tables:

CREATE OR REPLACE FUNCTION setmodtime() RETURNS TRIGGER AS '
BEGIN
NEW.modified_timestamp = now();
RETURN NEW;
END
' LANGUAGE 'plpgsql';

Is it possible to create only one function to insert rows in the corresponding
history table? the name of the history table can be constructed from the "original" table.
and I guess all fields of the table can be retrieved from the db's metadata.
Would that be feasible, and more importantly, would it be usable?

-Another question I have is for those who use this approach: How often o you have to flush those tables
and when you flush the tables, where do you put the flushed data? In another database on another server
or on tape?

Thanks.

Raph