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WorksheetsDBMS-Transactions-Revision
Total questions: 12
Worksheet time: 10mins
RAID stand for _________
Redundant Arrays of Idempotent Data
Redundant Arrays of Independent Disks
Redundant Arrays of Independent Data
Redundant Arrays of Isolated Disks
The files with variable length records make use of (a) structure for storage.
To preserve the integrity and consistency of data, the database system must ensure
Atomicity
Isolation
Durability
Consistency
All of the above
Consider the following action:
TRANSACTION.....
Commit;
ROLLBACK;
What does Rollback do?
Undoes the transactions before commit
Clears all transactions
Redoes the transactions before commit
No action
If a schedule S can be transformed into a schedule S' by a series of swaps of non-conflicting instructions, we say that S and S' are
Conflict serializable
Conflict equivalent
View serializable
Serializable
Consider the two transactions T1 and T2 and four schedules S1, S2, S3, S4 of T1 and T2 as given below
S1: R1(X); R2(X); R2(Y); W1(X); W1(Y); W2(Y)
S2: R1(X); R2(X); R2(Y); W1(X); W2(Y); W1(Y)
Here R1(X) denotes read operation on X by the transaction T1 and W1(X) denotes write operation on X by the transaction T1.
Which of the schedules(s) are conflicts serializable?
S1 and S2
S2 only
S1 only
Neither S1 nor S2
For the given schedule, which is the equivalent serial schedule?
T1 - T2 - T3
T1 - T3 - T2
T2 - T1 - T3
T3 - T1 - T2
The column ‘C’ has to be indexed. What is the content of the bitmap index?
A B C
a1 b1 c2
a1 b1 c2
a2 b4 c1
a3 b2 c3
Identify the options which are true for Immediate-modification scheme
Allows updates of an uncommitted transaction to be made to the buffer, or the disk itself, before the transaction commits.
Update log record must be written after a database item is written
Output of updated blocks to disk storage can take place at any time before or after transaction commit
Performs updates to buffer/disk only at the time of transaction commit
Consider the state of the transactions in the diagram and the statements given below:
A. T1 can be ignored.
B. T2 and T3 redone
C. T4 undone
D. T4 redone
Mark the correct group of statements from the options below
A, B, D
A, B, C
Only A and B but not C
Only B and C but not A
Identify the incorrect statement based on checkpoint
All updates are stopped while doing checkpoint
Continue scanning backwards till a record <Ti start> is found for every transaction Ti in L
Scan backwards from end of log to find the most recent <checkpoint L> record
Scan from starting of log to find the most recent <checkpoint L> record
What is the effect of the UNDO operation corresponding to a log record
< Ti; Y; S; K >
where Ti is the transaction, and S and K are the old and new values respectively of a data location
No change to Y
Writes the value S to Y
Writes the value K to Y
Sets Y to 0
