Transaction Timestamping in (Temporal) Databases

Many database applications need accountability and trace-ability that necessitate retaining previous database states. For a transaction-time database supporting this, the choice of times used to timestamp database records, to establish when records are or were current, needs to be consistent with a committed transaction serialization order. Previous solutions have chosen timestamps at commit time, selecting a time that agrees with commit order. However, SQL standard databases can require an earlier choice because a statement within a transaction may request “current time.” Managing timestamps chosen before a serialization order is established is the challenging problem we solve here. By building on two-phase locking concurrency control, we can delay a transaction’s choice of a timestamp, reducing the chance that transactions may need to be aborted in order keep timestamps consistent with a serialization order. Also, while timestamps stored with records in a transaction-time data...

• Type: Conference
• Year: 2001
• Where: VLDB
• Authors: Christian S. Jensen, David B. Lomet
• Keywords: Serialization Order, Timestamps, Transaction Serialization Order, VLDB 2001