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CUSTOMER_CODE
SMUDE
DIVISION_CODE
SMUDE
EVENT_CODE
APR2016
ASSESSMENT_CODE MCA3020_APR2016
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
18253
QUESTION_TEXT
Explain Temporal Database and Multimedia Database.
SCHEME OF
EVALUATION
Temporal Database: Temporal databases are used to record timereferenced data. Basically, majority of the database technologies are
temporal. For example: Record keeping function (inventory
administration, medical-record and personnel); Financial function
(banking, accounting and portfolio organization); Scientific function
(Weather monitoring), Scheduling function (project organization, hotel,
airline, and train reservations) all these functions trust on temporal
databases. (2 marks)
Temporal databases are best suited for the applications where
information as to organize on time constraints. Therefore temporal
database set a good example to demonstrate the requirement for
development of a combined set of concepts for the use of application
developers. The training of temporal database is designed by application
developers and designers. There are numerous applications where time is
an important factor in storing the information. For example: Insurance,
Healthcare, Reservation Systems, and Scientific Databases. (2 marks)
In case of temporal applications, even the two instances utilized might be
simply expanded. For example, in COMPANY database, it might be
desirable to keep PROJECT, JOB, and SALARY histories of all the
employees. It can be applied to UNIVERSITY database as well, to store
the grade history of STUDENT. The details about the YEAR,
SEMESTER, COURSE and each SECTION are also included in this
database.(1 mark)
Multimedia Database: Multimedia databases facilitate the users to store
as well as generate query for retrieving multimedia information. This
information can demand for: Documents (like articles/books/journals),
Images (like drawings/pictures), Video Clips (like
newsreels/movies/hone videos); Audio clips (like speeches/ phone
messages/ songs).(1 mark)
The primary type of database query generally tries to locate multimedia
sources comprising of particular objects of interest. Such as, one user
wants to locate all the video clips regarding aa specific person, say
Michael Jackson in a video database. Another scenario may be as of
someone willing to retrieve video clips grounded on specific activities
like, video clips where a soccer goal is scored by a certain player or
team. These type of queries are mentioned as content based retrieval, as
they retrieve information bases on a certain activity/object from the
multimedia sources.
(2 marks)
To make this retrieval fast, the multimedia database must make use of
some model to index and manage multimedia sources grounded on the
contents. But identifying the contents of multimedia sources is lengthy
and difficult task. To accomplish this task, two approaches can be
followed as defined below:
1.Based on automatic analysis of the multimedia sources. It is done to
recognize the contents mathematical characteristics.
2.Based on manual identification of the objects and objectives of interest
in each multimedia source. And later on depending on this information
index the sources.
(2 marks)
QUESTION_T
DESCRIPTIVE_QUESTION
YPE
QUESTION_ID 73630
QUESTION_T
Discuss any five SQL features in detail.
EXT
5 features - >2 marks each. Any 5 features among those mentioned below
SCHEME OF
EVALUATION may be written
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
73632
QUESTION_TEXT
What is database recovery management? Discuss three levels of
backup. State the methods and characteristics of transaction recovery.
SCHEME OF
EVALUATION
Definition – 1 mark 3 level – 3 marks 4 methods – 4 marks 2
characteristics – 2 marks
Data recovery is concerned with the restoring of database to an
accurate state in the occurance of a failure.
Levels: • full database backup (considers full backup of database)
• Differential back up (only the last variations that are performed on
the database are copied)
Transaction log backup (to back up those operations that are not
shown in a preceding backup copy of the database)
Methods: -
• write ahead protocol (makes sure that transaction logs are always
written before any database data that are really updated)
• Redundant transaction loga (make sure that a disk physical failure
will not harm the DBMS ability for recovering data
• Database buffers (used to accelerate disk operations)
• Database checkpoint (all updated buffers are written to the disk
by the DBMS)
Characteristics:• deferred write and deferred update (used by recovery process
sothat the transaction operations do not update the physical database
instantly)
• Write through (database is instantly updated by transaction
operations throughout the transaction’s execution, even before the
transaction arrives at its commit point)
QUESTION_T
DESCRIPTIVE_QUESTION
YPE
QUESTION_ID 73633
QUESTION_T What is data partitioning? What are the types of partitioning techniques?
Compare the various techniques.
EXT
Definition – 1 mark
I/O parallelism (Input/output parallelism) is the simplest type of parallelism.
This parallelism attempts to minimise the time required to retrieve relations
from disk by partitioning the relations on multiple disks. In this the input
data is partitioned and thereafter each partition is processed in parallel. The
results obtained are then combined after the processing of all partitioned
data. This technique greatly reduces the retrieval time. I/O parallelism is also
referred to as data partitioning.
3 types – 2 marks eachcomparison – 3 marks
Method in which rows acted on by the operation must be partitioned
SCHEME OF
between the query server processes.
EVALUATION
Types:- round robin (simple approach, best when all applications want to
access relation by scanning sequentially all of it on each and every query;
however not suitable for sophisticated access of the relation)
• Hash partitioning (select attributes as partitioning attributes. Helps to
avoid data skew. Suitable for applications which want only associative and
sequential access to data. Tuples are positioned by applying a hashing
function to any one attribute of each tuple)
• Range partitioning (the administrator chooses an attribute as the
partitioning attribute and specifies attribute values within a certain range to
be placed on certain disk. Helps to distribute a contiguous attribute value
ranges to each disk. Effective for grouping data and also sequential and
associative access)
Comparison
QUESTION_TYP
DESCRIPTIVE_QUESTION
E
QUESTION_ID
125273
QUESTION_TEX
Write a short note on Buffer Management.
T
SCHEME OF
EVALUATION
SQL Server uses buffer pages for any changes or requests for the data on
the database. These buffer pages are 8KB pages on RAM that minimizes
disc Input/Output. Any 8KB page can be buffered in memory, and set of
all pages currently buffered is called as buffer cache. The amount of
memory available to SQL Servers decides how many pages will be cached
in memory. The buffer cache is managed by Buffer Manager. Either
reading from or Writing to any page on the disc happens at two levels. The
data that should be either read/Written is first copied to the buffer cache
and the read/write operation is carried out on the data that is currently on
the Buffer Cache. The edited data is updated on the disc by the buffer
manager only if the in-memory cache has not been referenced for some
time. While writing pages back to the disc, asynchronous I/O is used
whereby the I/O operation is done in a background thread so that other
operations do not have to wait for the I/O operation to complete. Each
page is written with a checksum while they are written to the disc so that
while the data is referred back any time, the checksum mismatch would
detect the corruption of the data.
Data must be in RAM for DBMS to operate on it!
Buffer Mgr hides the fact that not all data is in RAM
Bufferpool information table contains: <frame#, pageid, pin_count,
dirty>
If requested page is not in pool:
Choose a frame for replacement.
Only “un-pinned” pages are candidates!
If frame is “dirty”, write it to disk
Read requested page into chosen frame
Pin the page and return its address
Requestor of page must eventually unpin it, and indicate whether page has
been modified:
dirty bit is used for this.
Page in pool may be requested many times,
a pin count is used.
To pin a page, pin_count++
A page is a candidate for replacement iff pin count == 0 (“unpinned”)
CC & recovery may entail additional I/O when a frame is chosen for
replacement.
Write-Ahead Log
protocol;
s
10mark
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
125275
QUESTION_TEXT
Discuss Semantic Query Optimization. What are the various Execution
Strategies for SQL Sub Queries?
SCHEME OF
EVALUATION
Semantic Query Execution: Semantic Query Execution is a technique to
modify one query into another query by using the relational database
constraints. These constraints may be unique attributes or much more
complex constraints. This technique is used for the efficient execution of
the query.
(1 mark)
Consider the example below:
Select E.LNAME, M.LNAME
FROM EMPLOYEE AS E, EMPLOYEE AS M
WHERE E.SUPERNO=M.ENO AND E.SALARY>M.SALARY
marks)
(2
This query retrieves the names of employees who earn more than their
supervisors. If a constraint is applied on the database schema to check
that none of the employee can earn more than his reporting supervisor;
the semantic query optimizer checks for this constraint and may not
execute the query if it knows that the resultant query will be empty. If
the constraint check is done efficiently then this approach can save a lot
of time.
(2 marks)
Execution Strategies for SQL Sub Queries: Different physical execution
strategies are employed by query optimizer for the various logical query
plan options. Two types of strategies are there for sub query execution:
1.
Navigational Strategies
2.
Set-Oriented Processing
(1 mark)
1.
Navigational Strategies: For executing sub-query, navigational
strategies depends on the nested loops joins. Basically there are two
classes of navigational strategies: forward lookup and reverse lookup.
Forward lookup firstly starts executing the outer query and when outer
rows are generated then it invokes the sub-query. Reverse lookup starts
with the sub-query and processes one sub-query row at a
time.
(2 marks)
2.
Set-Oriented Processing: Set-Oriented Processing finally needs that
the query could be effectively de-correlated. If this is the situation, set
operations for example hash, merge and join can execute the
query.
(2 marks)