I'm a bit fuzzy, but I think Vertica allows duplicating tables stored in multiple orders - then I think the appropriate version is picked automatically by the query optimiser. So this works not that differently to an index (which is also dbms managed performance denormalization).

There's also materialized views - if you have automatic incrementally updated materialized views, which are transparently substituted into queries, that's along these lines. I think there's a lot of progress being made here, and plenty of compromises used in the field that have been in production for a long time.

I think there's some ambitious work on materialized views being done in postgres.

> It gets mentioned in the Date/Darwen books as being the right way to do things, but no actual information seems to be given.

I don't think they ever convincingly got into the details on it.