This feature to implement multiversion concurrency control (MVCC) : when mutations within a transaction are applied, the values are written at the timestamp of their transaction.
该特性实现了多版本并发控制(MVCC)：当使用了事务时，在写入值时需要带上其事务的时间戳。
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Multiversion optimistic concurrency control (MVOCC) protocol and mobile transaction real-time commit (MTRTC) protocol are presented for mobile distributed real-time database systems (MDRTDBSs).