Changing Precision after insert

Newbie question, Is it possible to change the time precision of a measurement set after the points have already been inserted in a database?

We recently did a longterm datapull but mis-set the insert string to seconds precision so that the data isn’t just all just a few nano/milli-seconds on January 1st 1970. Although this is a bit humorous, it is inaccurate. Is it possible to increment the full dataset’s timestamp to our preferred precision in the db or do we need to pull out the entire set, scale it and then re-insert (in which case it may be better to just nuke it from orbit and rebuild)?

Thank you for the help!