Thomas Write Rule

In computer science, particularly the field of databases, the Thomas Write rule is a rule in timestamp-based concurrency control.

It states that, if a more recent transaction has already written the value of an object, then a less recent transaction does not need perform its own write since it will eventually be overwritten by the more recent one.

For example:

$\begin{bmatrix} T_1 & T_2 \\ & Read(A) \\ Read(B) & \\ &Write(C) \\ Write(C) & \\ Commit & \\ & Commit \end{bmatrix} \Longleftrightarrow \begin{bmatrix} T_1 & T_2 \\ & Read(A) \\ Read(B) & \\ & Write(C) \\ & \\ Commit & \\ & Commit\\ \end{bmatrix}$

Assuming that the timestamp of T1 is less than that of T2, T1's write is discarded.

If TS(T)Thomas Write Rule

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