> pretty sure the scada vendors partition the data in to tables so each table is a day or week of data, they do rollups on the data so the detail is available if you do a query with a 1 minute timespan but the data is already aggregated in to representative values for a 1 minute interval if the query timespan is 1 day.

I have not seen this, but if this is the case, and if these aggregates are stored in a proper relational database, that solves a big chunk of the problems people have with doing analytics on historian data.

As far as I know GE Proficy does not do this. Which is a pain.