COMP9315 Final Exam |
The University of New South Wales COMP9315 DBMS Implementation Final Exam |
DBMS Implementation |
Consider the following transactions:
T1: R(X) R(Y) W(X) W(Y) T2: W(X) R(Y) T3: R(Y) R(X) W(Y)
Note that above is not a schedule; it simply gives the sequence of read/write operations for each transaction. We assume that all transactions eventually commit successfully.
Using the transactions above, answer the following questions:
Add appropriate lock/unlock operations for a two-phase locking strategy.
Give a possible schedule that might arise from executing the transactions defined in part (a).
Add lock/unlock operations which are definitely not based on two-phase locking.
Give a possible schedule that might arise from executing the transactions defined in part (c).
In answering the questions above ...
show lock operations as follows:
use the following notation in giving schedules:
In other words, use the same kind of notation that is used on pages I-67 and I-69 of the Course Notes.
in giving possible schedules, you may use any order of operations that you wish, provided that
Show all working.
Instructions: