cs614 solved midterm paper fall 2010 december 5

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Data Warehousing cs614 papers

MIDTERM EXAMINATION

Spring 2010

CS614- Data Warehousing (Session - 6)

Ref No: 1368137

Time: 60 min

Marks: 40

Question No: 1 ( Marks: 1 ) - Please choose one
The need to synchronize data upon update is called
► Data Manipulation
► Data Replication
► Data Coherency
► Data Imitation

Question No: 2 ( Marks: 1 ) - Please choose one
Taken jointly, the extract programs or naturally evolving systems formed a spider web, also known as
► Distributed Systems Architecture
► Legacy Systems Architecture
► Online Systems Architecture
► Intranet Systems Architecture

Question No: 3 ( Marks: 1 ) - Please choose one
For good decision making, data should be integrated across the organization to cross the LoB (Line of Business). This is to give the total view of organization from:
► Owner’s Perspective
► Customer’s Perspective
► Decision Maker’s Perspective
► Employee's Perspective

Question No: 4 ( Marks: 1 ) - Please choose one
Node of a B-Tree is stored in memory block and traversing a B-Tree involves ______ page faults.
► O (n)
► O (n2)
► O (n lg n)
► O (lg n)

Question No: 5 ( Marks: 1 ) - Please choose one
Which statement is true for De-Normalization?
► Redundant data is a performance liability at query time, but is a performance benefit at update time.
► Redundant data is a performance benefit at both query time and update time.
► Redundant data is a performance liability at both query time and update time.
► Redundant data is a performance benefit at query time, but is a performance liability at update time.

Question No: 6 ( Marks: 1 ) - Please choose one
Pre-join technique is used to avoid
► Run time join
► Compile time join
► Load time join

Question No: 7 ( Marks: 1 ) - Please choose one
Cube is a __________ entity containing values of a certain fact at a certain aggregation level at an intersection of a combination of dimensions.
► Logical
► Physical
► Analytical
► None of these

Question No: 8 ( Marks: 1 ) - Please choose one
The goal of star schema design is to simplify ________
► Logical data model
► Physical data model
► Conceptual data model
► None of these

Question No: 9 ( Marks: 1 ) - Please choose one
Grain is the ________ level of data stored in the warehouse.
► Atomic
► Summarized
► Aggregated
► Cube

Question No: 10 ( Marks: 1 ) - Please choose one
Transactional fact tables do not have records for events that do not occur. These are called
► Not Recording Facts
► Fact-less Facts
► Null Facts
► None of these

Question No: 11 ( Marks: 1 ) - Please choose one
A ________ dimension is a collection of random transactional codes, flags and/text attributes that are unrelated to any particular dimension. The ______ dimension is simply a structure that provides a convenient place to store the ______ attributes.
► Junk
► Time
► Parallel
► None of these

Question No: 12 ( Marks: 1 ) - Please choose one
During ETL process of an organization, suppose you have data which can be transformed using any of the transformation method. Which of the following strategy will be your choice for least complexity?
► One-to-One Scalar Transformation
► One-to-Many Element Transformation
► Many-to-Many Element Transformation
► Many-to-One Element Transformation

Question No: 13 ( Marks: 1 ) - Please choose one
Change Data Capture is one of the challenging technical issues in _____________
► Data Extraction
► Data Loading
► Data Transformation
► Data Cleansing

Question No: 14 ( Marks: 1 ) - Please choose one
Rearranging the grouping of source data, delivering it to the destination database, and ensuring the quality of data are crucial to the process of loading the data warehouse. Data ____________ is vitally important to the overall health of a warehouse project.

1. Cleansing
2. Cleaning
3. Scrubbing
Which of the following options is true?
► Option 1 only
► Option 2 only
► Option 1 & 2 only
► Option 1, 2 & 3

Question No: 15 ( Marks: 1 ) - Please choose one
When performing objective assessments, companies follow a set of principles to develop metrics specific to their needs, there is hard to have “one size fits all” approach. Which of the following statement represents the pervasive functional forms?
► Simple Ratio, Min or Max Operation, Weighted Average
► Only Complex Ratio, Min Operation, Max Operation
► Only Simple Ratio, Min or Max Operation
► Only Min or Max Operation, Weighted Average

Question No: 16 ( Marks: 1 ) - Please choose one
The input to the data warehouse can come from OLTP or transactional system but not from other third party database.
► True
► False

Question No: 17 ( Marks: 1 ) - Please choose one
Normalization effects performance
► True
► False

Question No: 18 ( Marks: 1 ) - Please choose one
Collapsing tables can be done on the ___________ relationships
► One-to-One
► Many-to-Many
► Both One-to-One and Many-to-Many
► None of these

Question No: 19 ( Marks: 1 ) - Please choose one
_________ breaks a table into multiple tables based upon common column values.
► Horizontal splitting
► Vertical splitting

Question No: 20 ( Marks: 1 ) - Please choose one
If w is the window size and n is the size of data set, then the complexity of merging phase in BSN method is___________
► O (n)
► O (w)
► O (w n)
► O (w log n)

Question No: 21 ( Marks: 2 )
Briefly describe snowflake schema.

Ans:

Snowflake Schema: snowflaking is a method of normalizing the dimension tables in star schema. When we completely normalize all the dimension tables, then the resultent structure resemble a snowflakewith the fact table in the middle.






Question No: 22 ( Marks: 2 )
Why both aggregation and summarization are required?







Question No: 23 ( Marks: 3 )
Under what condition smart tools work properly to construct a less detailed aggregate from more detailed aggregate?



Ans:


Question No: 24 ( Marks: 3 )
What is web scraping? Give some of its uses.



Question No: 25 ( Marks: 5 )
After completing the transformation task, data loading activity is started. How many types of data loading strategies are and when each type of strategy is adopted? Explain.



Question No: 26 ( Marks: 5 )
What are the drawbacks of MOLAP? Also explain the curse of Dimensionality?