Gateforum Test Series: Databases - Transactions

Question

Which of the following time stamp ordering protocol(s) allow the following schedules?

$T:W_1(A)\ W_2(A)\ W_3(A)\ R_2(A)\ R_4(A)$

Time stamps: $T_1=5,T_2=10,T_3=15,T_4=20$

• A. Thomas write rule
• B. Multiversion time stamp protocol
• C. Basic Time stamp
• D. All of these

Comments

B?

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Yes..please explain

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i used option elimination because i don't know anything about Multi-version time stamp protocol

In basic time stamp rule,

$R_2(A): \ \ $ $TS(T_2) <  \text{Write-timestamp(A)}$

So $T_2$ wants to read item which is already overwritten so rollback. 

Same case with thomas write rule.

So i used option elimination and guessed B

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