Optional minMinimum dirtCount (number of discarded documents since the last vacuuming)
under which auto vacuum is not triggered. It defaults to 20.
Optional minMinimum dirtFactor (proportion of discarded documents over the total)
under which auto vacuum is not triggered. It defaults to 0.1.
Sets minimum thresholds for
dirtCountanddirtFactorthat trigger an automatic vacuuming.