如果autovacuum太慢,则应加快速度:
autovacuum_vacuum_cost_limit
ALTER TABLE tab SET (autovacuum_vacuum_cost_delay = 0);
then Autovacuum将不停下来运行。
maintenance_work_mem
autovacuum_multixact_freeze_max_age
ALTER TABLE tab SET (autovacuum_multixact_freeze_max_age = 50000000);