this has been great, thanks all for the input.

At the moment even pushing only about 150Gb a month we are getting about 14000 flows per 5 minute period during the day. I just assumed that if I kept 5 minute data for a week even managing to aggregate somewhat that I would still end up with tables with millions of records in it.

Having looked around the Postgres site maybe I'm being foolish :-) I will go with the one table and see how I go.

Thanks all for the advice it has made my life a lot easier.