It's called transaction id wraparound, and you don't want to allow it to happen. http://www.postgresql.org/docs/9.3/static/routine-vacuuming.html#VACUUM-FOR-WR

It's called transaction id wraparound, and you don't want to allow it to happen. http://www.postgresql.org/docs/9.3/static/routine-vacuuming.html#VACUUM-FOR-WRAPAROUND http://www.postgresql.org/docs/9.3/static/routine-vacuuming.... Fortunately the PostgreSQL has autovacuum so you probably don't need to worry about this.