ABSTRACT
In the two-phase-locking (2PL) model, the data manipulation language operation should need to have a write/read lock before it writes or reads a data item [86].
In the timestamp-ordering model, a unique timestamp is assigned to every data manipulation language operation and implements a read timestamp and a write timestamp for each data item [87]. When a data manipulation language operation is issued to read or write on the data item, this operation is allowed only if the read or the write timestamp of the data item is lower than the timestamp of the data manipulation language operation; otherwise, the operation will be rejected.
