Type: integer
Default: 50000000
Min: 0
Max: 1000000000
Context: user
Restart: false

Specifies the cutoff age (in transactions) that VACUUM should use to decide whether to trigger freezing of pages that have an older XID. 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.


Most users will want to decrease this so that rows which have been cold for a long time get frozen earlier, and avoid an autovacuum_freeze. The suggestion of 500000 is for a moderately busy database; do not set to less than a few hours worth of XIDs. Maximum setting is 1/2 of autovaccuum_max_freeze_age.