CoolInterview.com - World's Largest Collection of Interview Questions & Answers, FAQs, queries, sample papers, exam papers, dumps, what, why, how, where, when questions
Our Services
Get 9,000 Interview Questions & Answers in an eBook.




Get it now !!
Send your Resume to 6000 Companies
General Datawarehousing Interview Questions & Answers - Learning Mode
COOLINTERVIEW.COM DATA WAREHOUSING INTERVIEW QUESTIONS GENERAL DATAWAREHOUSING INTERVIEW QUESTIONS QUESTIONS & ANSWERS - LEARNING MODE

General Datawarehousing Interview Questions & Answers - Learning Mode

Data warehousing is the process of constructing and using a data warehouse. A data warehouse is constructed by integrating data from multiple heterogeneous sources that support analytical reporting, structured and/or ad hoc queries, and decision making. Data warehousing is the process of constructing and using a data warehouse. A data warehouse is constructed by integrating data from multiple heterogeneous sources that support analytical reporting, structured and/or ad hoc queries, and decision making.

Try General Datawarehousing Interview Questions & Answers - Exam Mode

1 2 3 Next

Sort By : Latest First | Oldest First | By Rating

General Datawarehousing Interview Questions & Answers - Learning Mode
Try General Datawarehousing Interview Questions & Answers - Exam Mode
Question: What type of Indexing mechanism do we need to use for a typical datawarehouse?

Answer: On the fact table it is best to use bitmap indexes. Dimension tables can use bitmap and/or the other types of clustered/non-clustered, unique/non-unique indexes.

To my knowledge, SQLServer does not support bitmap indexes. Only Oracle supports bitmaps. Source: CoolInterview.com
Question: What are Semi-additive and factless facts and in which scenario will you use such kinds of fact tables?

Answer: Snapshot facts are semi-additive, while we maintain aggregated facts we go for semi-additive.

EX: Average daily balance

A fact table without numeric fact columns is called factless fact table.

Ex: Promotion Facts

While maintain the promotion values of the transaction (ex: product samples) because this table doesn’t contain any measures.

Submitted by Srikanth M ( creku @ yahoo . com ) Source: CoolInterview.com
Question: What is VLDB?

Answer: VLDB stands for Very Large DataBase.

It is an environment or storage space managed by a relational database management system (RDBMS) consisting of vast quantities of information.

Submitted By: Francis C. ( xxchen74 @ hotmail . com )

_____________________

VLDB doesn’t refer to size of database or vast amount of information stored. It refers to the window of opportunity to take back up the database.

Window of opportunity refers to the time of interval and Source: CoolInterview.com
Question: What is the Difference between OLTP and OLAP?

Answer: Main Differences between OLTP and OLAP are:-

1. User and System Orientation

OLTP: customer-oriented, used for data analysis and querying by clerks, clients and IT professionals.

OLAP: market-oriented, used for data analysis by knowledge workers( managers, executives, analysis).

2. Data Contents

OLTP: manages current data, very detail-oriented.

OLAP: manages large amounts of historical data, provides facilities for summarization and aggregation, Source: CoolInterview.com
Question: What is a level of Granularity of a fact table?

Answer: Level of granularity means level of detail that you put into the fact table in a data warehouse. For example: Based on design you can decide to put the sales data in each transaction. Now, level of granularity would mean what detail are you willing to put for each transactional fact. Product sales with respect to each minute or you want to aggregate it upto minute and put that data. Source: CoolInterview.com
Question: What are the Different methods of loading Dimension tables?

Answer: Conventional Load:
Before loading the data, all the Table constraints will be checked against the data.

Direct load:(Faster Loading)
All the Constraints will be disabled. Data will be loaded directly.Later the data will be checked against the table constraints and the bad data won't be indexed.
Source: CoolInterview.com
Question: What is ODS?

Answer: 1. ODS means Operational Data Store.

Submitted by Francis C. ( xxchen74 @ hotmail . com )

2. A collection of operation or bases data that is extracted from operation databases and standardized, cleansed, consolidated, transformed, and loaded into an enterprise data architecture. An ODS is used to support data mining of operational data, or as the store for base data that is summarized for a data warehouse. The ODS may also be used to audit the data warehouse to assure summarized an Source: CoolInterview.com
Question: What is a general purpose scheduling tool?

Answer: The basic purpose of the scheduling tool in a DW Application is to stream line the flow of data from Source To Target at specific time or based on some condition.
Source: CoolInterview.com
Question: What is SCD1 , SCD2 , SCD3?

Answer: SCD Stands for Slowly changing dimensions.

SCD1: only maintained updated values.

Ex: a customer address modified we update existing record with new address.


SCD2: maintaining historical information and current information by using

A) Effective Date

B) Versions

C) Flags

or combination of these

SCD3: by adding new columns to target table we maintain historical information and curr Source: CoolInterview.com
Question: What are Aggregate tables?

Answer: Aggregate table contains the summary of existing warehouse data which is grouped to certain levels of dimensions.Retrieving the required data from the actual table, which have millions of records will take more time and also affects the server performance.To avoid this we can aggregate the table to certain required level and can use it.This tables reduces the load in the database server and increases the performance of the query and can retrieve the result very fastly. Source: CoolInterview.com
Question: Why are OLTP database designs not generally a good idea for a Data Warehouse?

Answer: Since in OLTP,tables are normalised and hence query response will be slow for end user and OLTP doesnot contain years of data and hence cannot be analysed.

Submitted by Venkat Mothukuri (VMothukuri@covansys.com) Source: CoolInterview.com
Question: What is Normalization, First Normal Form, Second Normal Form , Third Normal Form?

Answer: 1.Normalization is process for assigning attributes to entities?Reducesdata redundancies?Helps eliminate data anomalies?Produces controlledredundancies to link tables

2.Normalization is the analysis offunctional dependency between attributes / data items of userviews􀁺It reduces a complex user view to a set of small andstable subgroups of fields / relations

1NF:Repeating groups must beeliminated, Dependencies can be identified, All key attributesdefined,No repeating groups Source: CoolInterview.com
Question: Define pre-emptive and non-pre-emptive.

Answer: Premptive means taken as a measure against something possible, anticipated, or feared; preventive; deterrent: a preemptive tactic against a ruthless business rival.

Non Pre-emptive is the exact opposite to Pre-emptive.No such preventive measures has been taken. Source: CoolInterview.com
Question: What is ER Diagram?

Answer: The Entity-Relationship (ER) model was originally proposed by Peter in 1976 [Chen76] as a way to unify the network and relational database views.

Simply stated the ER model is a conceptual data model that views the real world as entities and relationships. A basic component of the model is the Entity-Relationship diagram which is used to visually represents data objects.

Since Chen wrote his paper the model has been extended and today it is commonly used for database design F Source: CoolInterview.com
Question: What is data mining?

Answer: Data mining is a process of extracting hidden trends within a datawarehouse. For example an insurance dataware house can be used to mine data for the most high risk people to insure in a certain geographial area. Source: CoolInterview.com
Question: Name some of modeling tools available in the Market?

Answer: These tools are used for Data/dimension modeling

1. Oracle Designer
2. ERWin (Entity Relationship for windows)
3. Informatica (Cubes/Dimensions)
4. Embarcadero
5. Power Designer Sybase Source: CoolInterview.com
Question: How are the Dimension tables designed?

Answer: Most dimension tables are designed using Normalization principles upto 2NF. In some instances they are further normalized to 3NF.

Find where data for this dimension are located.

Figure out how to extract this data.

Determine how to maintain changes to this dimension (see more on this in the next section).

Change fact table and DW population routines. Source: CoolInterview.com
Question: What are conformed dimensions?

Answer: Conformed dimensions mean the exact same thing with every possible fact table to which they are joined
Ex:Date Dimensions is connected all facts like Sales facts,Inventory facts..etc

Submitted by Srikanth M (creku @ yahoo . com ) Source: CoolInterview.com
Question: What are non-additive facts?

Answer: Non-Additive: Non-additive facts are facts that cannot
be summed up for any of the dimensions present in the
fact table.

Submitted by Avinash J (avikj@yahoo.com) Source: CoolInterview.com
Question: What does level of Granularity of a fact table signify?

Answer: Granularity
The first step in designing a fact table is to
determine the granularity of the fact table. By
granularity, we mean the lowest level of information
that will be stored in the fact table. This
constitutes two steps:

Determine which dimensions will be included.
Determine where along the hierarchy of each dimension
the information will be kept.
The determining factors usually goes back to the
requirements

Submitted by Avinash J (avikj@yahoo.co Source: CoolInterview.com

1 2 3 Next



India News Network
Latest 20 Questions
Payment of time- barred debt is: (a) Valid (b) Void (c) Illegal (d) Voidable
Consideration is defined in the Indian Contract Act,1872 in: (a) Section 2(f) (b) Section 2(e) (c) Section 2(g) (d) Section 2(d)
Which of the following is not an exception to the rule, "No consideration, No contract": (a) Natural love and affection (b) Compensation for involuntary services (c) Completed gift (d) Agency
Consideration must move at the desire of: (a) The promisor (b) The promisee (c) The promisor or any other party (d) Both the promisor and the promisee
An offer which is open for acceptance over a period of time is: (a) Cross Offer (b) Counter Offer (c) Standing Offer (d) Implied Offer
Specific offer can be communicated to__________ (a) All the parties of contract (b) General public in universe (c) Specific person (d) None of the above
_________ amounts to rejection of the original offer. (a) Cross offer (b) Special offer (c) Standing offer (d) Counter offer
A advertises to sell his old car by advertising in a newspaper. This offer is caleed: (a) General Offer (b) Special Offer (c) Continuing Offer (d) None of the above
In case a counter offer is made, the original offer stands: (a) Rejected (b) Accepted automatically (c) Accepted subject to certain modifications and variations (d) None of the above
In case of unenforceable contract having some technical defect, parties (a) Can sue upon it (b) Cannot sue upon it (c) Should consider it to be illegal (d) None of the above
If entire specified goods is perished before entering into contract of sale, the contract is (a) Valid (b) Void (c) Voidable (d) Cancelled
______________ contracts are also caled contracts with executed consideration. (a) Unilateral (b) Completed (c) Bilateral (d) Executory
A offers B to supply books @ Rs 100 each but B accepts the same with condition of 10% discount. This is a case of (a) Counter Offer (b) Cross Offer (c) Specific Offer (d) General Offer
_____________ is a game of chance. (a) Conditional Contract (b) Contingent Contract (c) Wagering Contract (d) Quasi Contract
There is no binding contract in case of _______ as one's offer cannot be constructed as acceptance (a) Cross Offer (b) Standing Offer (c) Counter Offer (d) Special Offer
An offer is made with an intention to have negotiation from other party. This type of offer is: (a) Invitation to offer (b) Valid offer (c) Voidable (d) None of the above
When an offer is made to the world at large, it is ____________ offer. (a) Counter (b) Special (c) General (d) None of the above
Implied contract even if not in writing or express words is perfectly _______________ if all the conditions are satisfied:- (a) Void (b) Voidable (c) Valid (d) Illegal
A specific offer can be accepted by ___________. (a) Any person (b) Any friend to offeror (c) The person to whom it is made (d) Any friend of offeree
An agreement toput a fire on a person's car is a ______: (a) Legal (b) Voidable (c) Valid (d) Illegal
Cache = 0.046875 Seconds