Hi,

it is not unusual for a subject area to have one 'formal' time dimension and then numerous date columns that are not part of the time dimension, but which act more like descriptor columns.

In your case, as the learned Mr @Christian Berg rightly says just because you want to calculate distinct issues opened and distinct issues closed does not require you to model additional time / calendar dimensions and doing so would probably only prove confusion to the users.

Your requirement needs no more than the dates in question and a count distinct

A subject area should be as simple as possible, but no simpler.

If you 'issue' requirement increases significantly then you might then want to consider making a wholly specialized issue subject area, with your open calendar and closed calendar, but, until the business need / case is sufficient I would suggest that the solution proffered is too.

Ok now you just keep adding things to your question.

a) Be precise with your question from the beginning:

b) Such wide-ranging and open-ended questions are either to be split up into precise detail questions or in your case something better discussed with a consultant since there seems to be some very basic questions that aren't asked or answered to begin with. Conceptual ones.

c) Regarding "So what if no record in fact table?" - that's one of THE conceptual questions which you must think about in the context of your solution first in terms of how to handle it. Because you are pretty much asking "how do I analyze something that doesn't exist". And whole there are solutions, this is really something you need to be clear about first.