CUSTOMER_CODE
SMUDE
DIVISION_CODE
SMUDE
EVENT_CODE
JAN2016
ASSESSMENT_CODE MCA3020_JAN2016
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
18249
QUESTION_TEXT
Explain various architectural approaches of OODBMS?
SCHEME OF
EVALUATION
1.Distributed Client Server Approach:
Client processes manage application specific activities like utilization
and updation of separate objects. These processes may be situated on the
same workstation or on dissimilar workstations. Usually a single server
will communicate with numerous clients providing simultaneous
requests for data which is managed by that server. There are three
different work-station server architectures that have been proposed for
OODBMS. They are as follows:
a.Object ServerApproach: A object is considered as the unit of transfer
from server to client. Both machines store objects and are competent of
performing methods on objects. Object-level locking is carried out
easily. The main disadvantage of this approach is the overhead related
with the server interaction needed to access each object.
b.Page Server Approach: In this approach, we consider page as the unit
of transfer from server to client. The overhead of object access is
decreased by the transfers of page level since it does not need server
interaction at all times. You can simplify the architecture and
implementation of the server as it needs only executing the services of
backend databases.
c.File Server Approach: In this approach, the client processes of
OODMBS have an interaction with a network file service for reading
and writing database steps. This approach makes the process of the
server implementation simpler because there is no need to manage
secondary storage. The main disadvantage of this approach is that it
requires two network interactions for accessing data.(4 marks)
2.Data Access Mechanism: Assessment of Object Oriented DBMS
products take into account the procedure required to shift data from
secondary store unit into a consumer application. Usually this
necessitates interaction with the server process, probably across one
network. Objects are stored into a consumer’s memory may need more
processing. The cost and procedure of releasing locks, and updated
objects that are returned to the server should be considered. (2 marks)
3.Object Clustering: The process of transferring units larger as compared
to an object is done under the supposition that an access of an application
to a specified object specifies a high possibility that it may also access
other related objects. When transferring number of objects, further server
interaction may not be required to assure these further object accesses.
Object clustering can be defined as the capability for an application to
offer information to the object oriented DBMS. This is done so that
objects which are usually accessed mutually can be accumulated close to
each other and therefore benefits from bulk transfers of data.(2 marks)
4.Heterogeneous Operation: In this approach, an object oriented DBMS
offers a method in which application can work together. This is done by
sharing access to a common group of objects. Numerous concurrent
applications are supported by a usual OODBMS; these applications are
executed on numerous processors which are connected through a local
area network. Frequently, the processors will be from dissimilar
computer companies where each company comprises its own data
representation formats. To make applications work together in this kind
of environment, data must be converted to the representation format
appropriate for the processor. (2 marks)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
18252
QUESTION_TEXT
Discuss Lorel Query Language. Differentiate between XML Oriented
Databases and Native XML Databases.
SCHEME OF
EVALUATION
Lorel Query Language:Lorel is considered as an early query language
used for semi structured data. Lorel language makes use of the OEM
(Object Exchange Model) as the data model for semi structured data.
Lorel is utilized to expandOQL (Object Query Language) for the
procedure of querying elements. This is done by depending on coercion
at various levels to hold back the powerful typing of OQL. Lorel is also
used to extend OQL with path expressions. This is done in order that
user can state the patterns that are corresponding to actual paths in
referred data.(4 marks)
One of the advantages of Lorel language is its easy syntax which makes
users to understand it more clearly. The drawback of Lorel language is
that it is dependent on OQL parser. Also it comprises of limited
functionalities. (2 marks)
Differences between XML Oriented Databases and Native XML
Databases: XML-oriented databases are typically relational and enclose
model or pattern driven extensions for transporting data to and from
XML documents and are usually intended for data-centric documents.
Following are the differences between XML Oriented Databases and
Native XML Databases:
1.A native XML database is used to maintain physical structure. An
XML-oriented database can do so also, but practice shows a diverse
story.
2.Native XML database can accumulate data without schema. We could
make use of techniques to recognize structure in unprocessed documents
to be accumulated in XML-oriented systems. These types of techniques
are relatively limited.
3.XPath, DOM, or comparable XML-associates APIs are required to
access data in native XML systems. Alternatively, XML-oriented
systems provide direct access to the data via open-standard APIs, like
open database connectivity (ODBC).
(4 marks)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
73629
QUESTION_TEXT
What are the different models of DBMS? State two advantages of each
type.
SCHEME OF
EVALUATION
5 models with advantages - >2 marks each. Any two advantages among
those mentioned below may be written
Hierarchical
Simplicity (simple design process since data consists of hierarchical
relationship), Security (can execute the changing level of security
characteristics), Database integrity (possible due to inbuilt structure of
parent and child), Relationship handling (proficient for relationships of
the type 1:M)
Network
Simplicity (simple design process since instances of data relationship
occur as N:M type), Flexibility (more flexible as you can navigate data
items in many ways), Standards (include development of worldwide
standards), Relationship handling (proficient for relationships of the
type N:M – popular in real data relationship situations)
Relational
Simplicity simple design process since easy to handle RDBMS), Flexibility
(more flexibity), Follow every mathematical theory (obeys theories in
maths), Relationship handling (can handle any every type of
relationship)
Object relational
Reusability (occurs from reuse and sharing), Flexibility (flexible but not
more flexible than RDBMS), Abstraction (permits developers of
software to incorporate their individual types and techniques applied to
DBMS), Relationship managing (helps in gathering records effortlessly)
Object
Relationship handling (can handle any every type of relationship), Use
of navigational interfaces – hence better than other models
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
between the query server processes.
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
SCHEME OF
EVALUATION 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_TYPE DESCRIPTIVE_QUESTION
QUESTION_ID
125274
QUESTION_TEXT Explain Fifth Normal Form (5NF).
Fifth normal form is the highest normal form used in relational database
design. It is mostly used when there is a large relational database.
The fifth normal form has developed by an IBM researcher, Ronald
Fagin. According to the Fagin’s theorem, “The original table must be
reconstructed from the tables into which it has been decomposed.” 5NF
allows decomposing a relation into three or more relations.
5NF is based on the concept of join dependency. Join dependency means
that a relation, after being broken down into 3 or more smaller relations,
should be capable of being combined all over again on similar key to
result in the creation of the original table. The join dependency is more
general form of multi-valued dependency.
(2 marks)
A relation (R) meets the condition of fifth normal form (R1, R2, ……Rn)
if and only if R is equal to the join of R1, R2, ……Rn (Here, Ri are
subsets of set of attributes of R)
SCHEME OF
EVALUATION
Any relation R is said to be in 5NF or PJNF (Project-Join Normal Form)
if foe all join dependencies in any case one of the following holds.
(a) (R1, R2, ……Rn) is trivial join-dependency (that is one of Rt is R)
(b) Every Riis an candidate key for relation R.
(2 marks)
Definition of Fifth Normal Form: A relation should be in fifth normal
form (5NF) if and only if all join dependency in the table is connected by
candidate keys of the relation.
(2 marks)
The table before Fifth Normal Form:
The table after Fifth Normal Form:
(4 marks)
QUESTION_TYPE
DESCRIPTIVE_QUESTION
QUESTION_ID
125275
QUESTION_TEXT
Discuss Semantic Query Optimization. What are the various Execution
Strategies for SQL Sub Queries?
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)
SCHEME OF
EVALUATION
(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)