ancient history mark and rolling back data

Hello,

From reading it seems historical data beyond the current epoch marker are eligible for purge and can never be recoverable..

What is the best approach for an organization who wants the ability to revert to a previous day or week's snapshot?  

Should they configure the AHM to advance on a daily or weekly basis (rather than the default value)?  Is that going to degrade the performance too much (too many delete vectors)?

Or, is there some other mechanism to recover previous snapshot in Vertica which is completely unrelated to the AHM marker?


Another question:  Can AHM related settings be confined to specific schemas?


Thanks!