Specifies the cutoff age (in transactions) that VACUUM should use to decide whether to replace transaction IDs with
FrozenXID while scanning a table. The default is 50 million transactions. Although users can set this value anywhere from zero to one billion, VACUUM will silently limit the effective value to half the value of autovacuum_freeze_max_age, so that there is not an unreasonably short time between forced autovacuums. For more information see vacuum-for-wraparound.