The following table presents the lock requests by transactions T1, T2, T3, and T4. S(.) and X(.) stand for 'shared lock' and exclusive lock', respectively. To prevent deadlocks, use a lock manager that uses the Wait-Die policy. Assume the four transactions have priority: T1< T2

Oracle 12c: SQL
3rd Edition
ISBN:9781305251038
Author:Joan Casteel
Publisher:Joan Casteel
Chapter5: Data Manipulation And Transaction Control
Section: Chapter Questions
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The following table presents the lock requests by transactions T1, T2, T3, and T4. S(.) and X(.) stand for shared lock' and `exclusive lock', respectively.
To prevent deadlocks, use a lock manager that uses the Wait-Die policy. Assume the four transactions have priority: T1 < T2 <T3 < T4. Determine which lock request
will be 'granted', 'blocked' or 'aborted'; for 'abort', specify which transaction is aborted, e.g., 'Tj aborts'.
time
t4
S(A)
X(D) | X(C)
t1
t2
t3
t5
to
t7
t8
X(B)
T2
T3
T4
S(C)
X(A)
X(B)
S(D)
O a
g, g, g, T1 aborts, g, T2 aborts, g, g
Ob.
g, g, g, b, g, T2 aborts, g, g
Oc.
g, g, g, T1 aborts, g, b, g, g
O d. g, g, g, T2 aborts, g, T1 aborts, g, g
Clear my choice
Transcribed Image Text:The following table presents the lock requests by transactions T1, T2, T3, and T4. S(.) and X(.) stand for shared lock' and `exclusive lock', respectively. To prevent deadlocks, use a lock manager that uses the Wait-Die policy. Assume the four transactions have priority: T1 < T2 <T3 < T4. Determine which lock request will be 'granted', 'blocked' or 'aborted'; for 'abort', specify which transaction is aborted, e.g., 'Tj aborts'. time t4 S(A) X(D) | X(C) t1 t2 t3 t5 to t7 t8 X(B) T2 T3 T4 S(C) X(A) X(B) S(D) O a g, g, g, T1 aborts, g, T2 aborts, g, g Ob. g, g, g, b, g, T2 aborts, g, g Oc. g, g, g, T1 aborts, g, b, g, g O d. g, g, g, T2 aborts, g, T1 aborts, g, g Clear my choice
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