CUSTOMER_CODE
SMUDE
DIVISION_CODE
SMUDE
EVENT_CODE
OCTOBER15
ASSESSMENT_CODE BC0050_OCTOBER15
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
4177
QUESTION_TEXT
What are the different goals of transaction management? Explain.
SCHEME OF
EVALUATION
The goal of the transaction management in a distributed database is to
control the execution of transactions so that:
1.Transactions have atomicity, durability, serializabilty and isolation
properties.
2.Their cost in terms of main memory, CPU and number of transmitted
control messages and their response time are minimized.
3.The availability of the system is maximized. (3 marks)
CPU and main memory utilization: It s a common aspect in both
centralized and distributed database. In case of concurrent transactions
the CPU and main memory should be properly scheduled and managed
by the operating system. Otherwise it becomes a bottle neck when the
number concurrent transaction is more. (2.5 marks)
Control messages: As the control message does not carry any fruitful
data and only they are used to control the execution of transactions.
There should be very less exchange of such messages between the sites.
The obvious reason is the communication cost will be increased
unnecessarily. (2.5 marks)
Response time should be as small as possible for the better performance
of the system. Definitely it will be very crucial as in distributed system
an additional time is required for communication between different sites.
(2 marks) Total 10 marks
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
4178
QUESTION_TEXT
List out the memory components of SGA. Explain
Memory components are
a.Redo log buffer
b.The database buffer cache
SCHEME OF EVALUATION c.The shared pool
d.The Java pool
e.The large pool
f.The streams pool
(1 mark)
Explanation:
For each type 1.5 marks each
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
72868
QUESTION_TEXT
Explain any 4 physical files of the database.
SCHEME OF EVALUATION
Datafiles
Control files
Parameter file
Archive file
(Each with Explanation 2.5*4)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
113961
QUESTION_TEXT
Give the 7 steps to be performed by each node except the commit point
site in the prepare phase of two phase commit mechanism. Also give the
3 steps occurring during forget phase.
Steps in the Prepare Phase: To complete the prepare phase, each node
excluding the commit point site performs the following steps:
1.
2.
3.
4.
SCHEME OF
EVALUATION
5.
6.
7.
The node requests that its descendants, that is, the nodes
subsequently referenced, prepare to commit.
The node checks to see whether the transaction changes data on
itself or its descendants. If there is no change to the data, then the
node skips the remaining steps and returns a read-only response
The node allocates the resources it needs to commit the transaction
if data is changed.
The node saves redo records corresponding to changes made by the
transaction to its online redo log.
The node guarantees that locks held for the transaction are able to
survive a failure.
The node responds to the initiating node with a prepared response
or, if its attempt or the attempt of one of its descendents to prepare
was unsuccessful, with an abort response.
These actions guarantee that the node can subsequently commit or
roll back the transaction on the node. The prepared nodes then wait
until a COMMIT or ABORT request is received from the global
coordinator.
(1 mark each)
Forget Phase: After the participating nodes notify the commit point site that
they have committed, the commit point site can forget about the transaction.
The following steps occur:
1.
After receiving notice from the global coordinator that all nodes
have committed, the commit point site erases status information
about this transaction.
2. The commit point site informs the global coordinator that it has
erased the status information.
3. The global coordinator erases its own information about the
transaction.
(1 mark each)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
113963
Give the two main goals of parallelism in a disk system. Also explain the
following RAID levels briefly:
QUESTION_TEXT
a.
RAID level 0
b.
RAID level 1
c.
RAID level 2
d.
RAID level 3
There are two main goals of parallelism in a disk system
1. Load -balance multiple small accesses, so that the throughput of such
accesses increases.
2. Parallelize large accesses so that the response time of large accesses is
reduced.
SCHEME OF
EVALUATION
(1 mark each)
RAID level 0 refers to disk arrays with striping at the level of blocks, but
without any redundancy. Figure (a) shows an array of size 4.
RAID level 1 refers to disk mirroring with block. Figure (b) shows a mirrored
organization that holds four disks worth of data.
RAID level 2 known as memory-style error correcting-code (ECC) organization,
employs parity bits. Memory systems have long used parity bits for error
detection and correction.
RAID level 3, bit-interleaved parity organization, improves on level 2 by
exploiting the fact that disk controllers, unlike memory systems, can detect
whether a sector has been read correctly, so the single parity bit can be used
for error correction, as well as for detection.
(2 marks each)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
113964
QUESTION_TEXT
List the main motivations of Distributed Databases. Explain
them
SCHEME OF
EVALUATION
Listing:
1.
Organizational and economic reasons
2.
Usage and interconnection of existing databases
3.
Incremental growth of an organization
4.
Reduced communication overhead
5.
Performance aspects
6.
Increased reliability and availability
(1 mark)
Explanation:
(1.5 marks each)