Transaction id wraparound. Transaction ids are 32 bit and they are used in a ring like manner, so a transaction id can only be reused if there are no open trans

Transaction id wraparound. Transaction ids are 32 bit and they are used in a ring like manner, so a transaction id can only be reused if there are no open transactions before it. If you (accidentally) keep a transaction open for a long time, then after a while you run out of transaction ids, and it is tough to recover from, because management operations themselves involve creating transactions.