accumulating fact question

i have an accumulating fact table that basically is a subscription fact. it joins people to groups. people subscribe and unsubscribe to a group. my fact table has a subscribe date key and an unsubscribe date key, both FKs to our date dimension. when the person is subscribed and not unsubscribed, what should i set the unsubscribe date key to? do i need to create a record with a high value for the date? like year 9999?

i dont want to make the unsubscribe date key NULLable.

thanks

If the subscription has an expiration date, you may want to use that. Otherwise reference a high date such as 12/31/9999. Discuss it with the business.

Use the same value as all of your other dimensions that are not applicable.