? huddle formats ? - I guess could be a table with rows like:
But, that does not seem to fit with: *some 1000 records for 100 years*
One year has max 366 valid dates => 100 years have < 36600 valid dates. One
record for every valid date would be sufficient. For every crude format, you
would have a seperate column (other columns could be there for quarter, day
of week, business week, egg week, what ever you would need. Joining this to
your tables will be very fast in all situations...