Within SAS Base, I humbly disagree, especially considering a possible data/observation count scaling issue - you may want to consider using SAS PROC DATASETS and the AGE processing to create/maintain a defined set of "cycles". Of course, if the cycle location of an observation (for a given MONTH or whatever selection you may use) is undetermined, then AGE / cycles will likely not work effectively and a single file with a WHERE statement for filtering will be more applicable.
Regardless, hopefully this type of "master" file/cycle approach warrants a "frequent" backup copy, in case a recovery/restore situation is warranted?
Scott Barry
SBBWorks, Inc.