NIELIT 2017 OCT Scientific Assistant A (IT) - Section B: 31

Question

When transaction $Ti$ requests a data item currently held by $Tj,Ti$ is allowed to wait only if it has a time stamp smaller than that of $Tj$ (that is $Ti$ is order than Tj). Otherwise, $Ti$ is rolled back (dies). This is

• A. Wait-die
• B. Wait-wound
• C. Wound-wait
• D. Wait

Comments

ANS : A  WAIT DIE

In this method, if a transaction requests to lock a resource (data item), which is already held with a conflicting lock by another transaction,

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https://gateoverflow.in/336922/Nielit-2017-oct-scientific-assistant-a-cs-section-c-10

Answer 1

WAIT-DIE METHOD

In this method, if a transaction requests to lock a resource (data item), which is already held with a conflicting lock by another transaction, then
one of the two possibilities may occur 

 

1• If $TS(T_{i})$ < $TS(T_{j};) $

• that is$ T_{i}$ which is requesting a conflicting lock, is older than $T_{j}$
• then $T_{i}$ is allowed to wait until the data-item is available.

 

2• $If TS(T_{i}) > TS(T_{j})$

•  that is $T_{i}$ is younger than $T_{j}$ . Then$ T_{i}$ dies.
•  $T_{i}$ is restarted later with a random delay but with the same timestamp.This method allows the older transaction to wait but kills the younger one.