OLAP Interview Questions & Answers

  1. Question 1. Explain About Olap ?

    Answer :

    OLAP is known as online analytical processing which provides answers to queries which are multi dimensional in nature. It composes relational reporting and data mining for providing solutions to business intelligence. This term OLAP is created from the term OLTP.

  2. Question 2. Explain About The Functionality Of Olap?

    Answer :

    Hyper cube or multidimensional cube forms the core of OLAP system. This consists of measures which are arranged according to dimensions. Hyper cube Meta data is created by star or snow flake schema of tables in RDBMS. Dimensions are extracted from dimension table and measures from the fact table.

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  4. Question 3. Explain About Molap?

    Answer :

    Classic form of OLAP is known as MOLAP and it is often called as OLAP. Simple database structures such as time period, product, location, etc are used. Functioning of each and every dimension or data structure is defined by one or more hierarchies.

  5. Question 4. Explain About Rolap?

    Answer :

    Functioning of ROLAP occurs simultaneously with relational databases. Data and tables are stored as relational tables. To hold new information or data new tables are created. Functioning of ROLAP depends upon specialized schema design.

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  7. Question 5. Explain About Aggregations?

    Answer :

    OLAP can process complex queries and give the output in less than 0.1 seconds, for it to achieve such a performance OLAP uses aggregations. Aggregations are built by aggregating and changing the data along the dimensions. Possible combination of aggregations can be determined by the combination possibilities of dimension granularities.

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  9. Question 6. Explain About The View Selection Problem?

    Answer :

    Often calculating all the data is not possible by aggregations for this reason some of the complex data problems are solved. In order to determine which data should be solved and calculated, developers use View selection application. This solution is often used to reduce calculation problem.

  10. Question 7. Explain About The Role Of Bitmap Indexes To Solve Aggregation Problems?

    Answer :

    Bitmaps are very useful in start schema to join large databases to small databases. Answer queries and bit arrays are used to perform logical operations on the databases. Bit map indexes are very efficient in handling Gender differentiation; also repetitive tasks are performed with much larger efficiency.

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  12. Question 8. Explain About Encoding Technique Used In Bitmaps Indexes?

    Answer :

    Bitmaps commonly use one bitmap for every single distinct value. Number of bitmaps used can be reduced by opting for a different type of encoding. Space can be optimized but when a query is generated bitmaps have to be accessed.

  13. Question 9. Explain About Binning?

    Answer :

    Binning process is very useful to save space. Performance may vary depending upon the query generated sometimes solution to a query can come within few seconds and sometimes it may take longer time. Binning process holds multiple values in the same bin.

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  15. Question 10. Explain About Candidate Check?

    Answer :

    The process which is underlined during the check of base data is known as candidate check. When performing candidate check performance varies either towards the positive side or to the negative side. Performance of candidate check depends upon the user query and also they examine the base data.

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  17. Question 11. Explain About Hybrid Olap?

    Answer :

    When a database developer uses Hybrid OLAP it divides the data between relational and specialized storage. In some particular modifications a HOLAP database may store huge amounts of data in its relational tables. Specialized data storage is used to store data which is less detailed and more aggregate.

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  19. Question 12. Explain About Api`s Of Olap?

    Answer :

    Microsoft in the late 1997 introduced a standard API known as OLE DB. After which XML was used for analysis specification and this specification was largely used by many vendors throughout the world as a standard specification. MDX is the standards specification for OLAP.

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  21. Question 13. Explain About Shared Features Of Olap?

    Answer :

    Shared implements most of the security features into OLAP. If multiple accesses are required admin can make necessary changes. The default security level for all OLAP products is read only. For multiple updates it is predominant to make necessary security changes.

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  23. Question 14. Explain About Analysis?

    Answer :

    Analysis defines about the logical and statistical analysis required for an efficient output. This involves writing of code and performing calculations, but most part of these languages does not require complex programming language knowledge. There are many specific features which are included such as time analysis, currency translation, etc.

  24. Question 15. Explain About Multidimensional Features Present In Olap?

    Answer :

    Multidimensional support is very essential if we are to include multiple hierarchies in our data analysis. Multidimensional feature allows a user to analyze business and organization. OLAP efficiently handles support for multidimensional features.

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  26. Question 16. Explain About The Database Marketing Application Of Olap?

    Answer :

    Database marketing tool or application helps a user or marketing professional in determining the right tool or strategy for his valuable add campaign. This tool collects data from all sources and gives relevant information the specialist with their add campaign. It gives a complete picture to the developer.

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  28. Question 17. What Are The Different Industries Which Use This Marketing Tool?

    Answer :

    Many different companies can use this tool for developing their business strategy but it is often three major industries which use this tool more. Those three industries are Consumer goods industries, Retail industries, and financial services industry. These industry`s have huge amount of data in their disposal which makes then to use these tools to determine their exact customer.

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  30. Question 18. What Is The Difference Between Olap And Dss?

    Answer :

    DSS, Decision Support System, as the name suggests, helps in taking decisions for top executive professionals. Data accessing, time-series data manipulation of an enterprise’s internal / some times external data is emphasized by DSS. The manipulation is done by tailor made tools that are task specific and operators and general tools for providing additional functionality.

    OLAP, Online Analysis Processing, is capable of providing highest level of functionality and support for decision which is linked for analyzing large collections of historical data. The functionality of an OLAP tool is purely based on the existing / current data.

    Software is a result of understanding the need of the client, and then building something which meets the client’s objectives. In area of software, the requirements change very frequently and thus processes need to be in place to manage various activities which would result in the production since the very beginning. Processes allow for planning, managing, operating, implementing, and monitoring tasks efficiently.

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  32. Question 19. Explain Why Process Improvement Leads To Product Improvement?

    Answer :

    Process improvement focuses on improving an organization’s processes to achieve results more efficiently. The emphasis is not on “what to build” but on “how to build”. It reduces inefficiencies in processes to achieve same objectives with better utilization of resources. Process improvement highlights the following:

    Define organizational goals
    Identify organization’s clients

    Align processes to realize organizational goals in order to satisfy the clients.
    All this leads to creation of a more efficient product to satisfy the clients better. Process improvement leads to product improvement as it removes inefficiencies from various processes to build a better quality product and in a more efficient manner.

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  34. Question 20. What Is The Difference Between Etl Tool And Olap Tool?

    Answer :

    ETL can extract, transform using various transformations that are available in the tool, and aggregate the data. The output can be used as an input for OLAP tool. ETL is the initial part of data warehousing. For generating cross tab report from the source tables, data warehouse takes very long time span. For efficiency, these tables are transformed into cubes and persisted in OLAP server. The analysis that is performed on the cubes is provided with pre-aggregated values. Hence, report generation will be much faster.

    OLAP supports online reports after performing certain join operations and creating some cubes. OLAP consists of various applications for score carding, reporting, dashboards, consolidation, planning, analysis, master data management, workspace and foundation.

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  36. Question 21. What Is Hybrid Olap?

    Answer :

    Hybrid OLAP is a mode of storage that uses a combination of multidimensional data structures and relational database tables for storing multidimensional data. The analysis services stores the aggregations for a HOLAP partition in a multidimensional structure and the facts are stored in relational database.

  37. Question 22. What Is Candidate Check?

    Answer :

    Candidate check is a process that triggered during checking the base data. The performance of candidate check varies either towards the positive side or to the negative side. The overall performance of the candidate check is dependent on the query submitted by the user and also on the examining the base data.

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  39. Question 23. What Is Binning?

    Answer :

    Space saving can be achieved by a process called ‘binning’. The performance could vary based on the generated query, and at times query solution can come in a few seconds and sometimes it could take more time. Binning process allows multiple values to be held up in the same bin.

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  41. Question 24. Explain The Encoding Technique Used In Bitmaps Indexes?

    Answer :

    One bitmap is commonly used for every single distinct value. When opted for different types of encoding, the number of bitmaps could be reduced. Space optimization can be achieved, except when the query is generated; bit maps need to be accessed.

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  43. Question 25. Explain The Role Of Bitmap Indexes To Solve Aggregation Problems?

    Answer :

    Bitmaps are useful for starting schema for the purpose of joining large databases small databases. For performing logical operations on the databases, bit arrays and the answer queries are used. To handle Gender differentiation, bit map indexes are efficient. Bit map indexes also capable of performing repetitive tasks with much larger efficiency.

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  45. Question 26. What Are Molap And Rolap?

    Answer :

    MOLAP: A more traditional way of OLAP analysis. Data is persisted in a multidimensional cube in MOLAP. The storage is in proprietary formats but not in the relational database. MOLAP data cubes are built in such a way that data retrieval is faster and are optimal for dicing and slicing operations.

    ROLAP: A methodology that is relied on manipulating the persisted data in the relational database, for providing an appearance of traditional OLAP’s dicing and slicing functionality. The actions of slicing and dicing are equivalent to adding the ‘WHERE’ clause in the SQL statement, is the essential part of ROLAP. The amount of data is not limited by ROLAP itself, thus able to handle large amounts of data.

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  47. Question 27. Explain The Functionality Of Olap?

    Answer :

    OLAP functionality is performed using SQL Anywhere by utilizing various extensions to SQL statements and window functions. Multidimensional data analysis, data mining, trend analysis, goal seeking, cost allocations, time series analyses and altering exceptions can be performed with a single SQL statement.

    Extensions to SELECT statement: Grouping input rows, analyze the groups and including the findings in the final result, are the operations that could be done in SELECT statement. They include extensions to GROUP BY clause – GROUING SETS, CUBE and ROLLUP clauses and WINDOW clause.

    WINDOW aggregate functions: Configurable sliding window concept is supported for using aggregate functions, which moves down the input rows as they are processed. Computing percentiles, moving averages and cumulative sums are performed in a single SQL statement, which reduces the complexity of using self-joins, correlated sub queries, temporary tables and at times, the combination of all these three.

    Window ranking functions: These functions facilitates to form a single statement SQL queries , to obtain the information , like shipped top ten products in a given year by total sales.

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  49. Question 28. What Is Uml?

    Answer :

    UML is Unified Modeling Language. It is a graphical language for visualizing specifying constructing and documenting the artifacts of the system. It allows you to create a blue print of all the aspects of the system, before actually physically implementing the system.

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  51. Question 29. What Is Modeling? What Are The Advantages Of Creating A Model?

    Answer :

    Modeling is a proven and well-accepted engineering technique which helps build a model. Model is a simplification of reality; it is a blueprint of the actual system that needs to be built. Model helps to visualize the system. Model helps to specify the structural and behavior of the system. Model helps make templates for constructing the system. Model helps document the system.

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  53. Question 30. What Are The Different Views That Are Considered When Building An Object-oriented Software System?

    Answer :

    Normally there are 5 views.

    Use Case view – This view exposes the requirements of a system.

    Design View – Capturing the vocabulary.

    Process View – modeling the distribution of the systems processes and threads. Implementation view – addressing the physical implementation of the system.

    Deployment view – focus on the modeling the components required for deploying the system.

  54. Question 31. What Are Diagrams?

    Answer :

    Diagrams are graphical representation of a set of elements most often shown made of things and associations.

  55. Question 32. What Are The Major Three Types Of Modeling Used?

    Answer :

    Major three types of modeling are structural, behavioral, and architectural.

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  57. Question 33. Mention The Different Kinds Of Modeling Diagrams Used?

    Answer :

    Modeling diagrams that are commonly used are, there are 9 of them. Use case diagram, Class Diagram, Object Diagram, Sequence Diagram, statechart Diagram, Collaboration Diagram, Activity Diagram, Component diagram, Deployment Diagram.

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  59. Question 34. What Is Architecture?

    Answer :

    Architecture is not only taking care of the structural and behavioral aspect of a software system but also taking into account the software usage, functionality, performance, reuse, economic and technology constraints.

  60. Question 35. What Is Sdlc?

    Answer :

    SDLC is Software Development Life Cycle. SDLC of a system included processes that are Use case driven, Architecture centric and Iterative and Incremental. This Life cycle is divided into phases. Phase is a time span between two milestones. The milestones are Inception, Elaboration, Construction, and Transition. Process Workflows that evolve through these phase are Business Modeling, Requirement gathering, Analysis and Design, Implementation, Testing, Deployment. Supporting Workflows are Configuration and change management, Project management.

  61. Question 36. What Are Relationships?

    Answer :

    There are different kinds of relationships: Dependencies, Generalization, and Association. Dependencies are relations ships between two entities that that a change in specification of one thing may affect another thing. Most commonly it is used to show that one class uses another class as an argument in the signature of the operation. Generalization is relationships specified in the class subclass scenario, it is shown when one entity inherits from other. Associations are structural relationships that are: a room has walls, Person works for a company. Aggregation is a type of association where there is a has a relation ship, That is a room has walls, ño if there are two classes room and walls then the relation ship is called a association and further defined as an aggregation.

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  63. Question 37. What Are Messages?

    Answer :

    A message is the specification of a communication, when a message is passed that results in action that is in turn an executable statement.

  64. Question 38. What Is An Use Case?

    Answer :

    A use case specifies the behavior of a system or a part of a system, all use cases are used to capture the behavior that need to be developed. It involves the interaction of actors and the system.

  65. Question 39. Explain The Rationale Behind Object Oriented Concepts?

    Answer :

    Object oriented concepts form the base of all modern programming languages. Understanding the basic concepts of object-orientation helps a developer to use various modern day programming languages, more effectively.

  66. Question 40. Explain About Object Oriented Programming?

    Answer :

    Object oriented programming is one of the most popular methodologies in software development. It offers a powerful model for creating computer programs. It speeds the program development process, improves maintenance and enhances reusability of programs.

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  68. Question 41. Explain What Is An Object?

    Answer :

    An object is a combination of messages and data. Objects can receive and send messages and use messages to interact with each other. The messages contain information that is to be passed to the recipient object.

  69. Question 42. Explain The Implementation Phase With Respect To Oop?

    Answer :

    The design phase is followed by OOP, which is the implementation phase. OOP provides specifications for writing programs in a programming language. During the implementation phase, programming is done as per the requirements gathered during the analysis and design phases.

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  71. Question 43. Explain About The Design Phase?

    Answer :

    In the design phase, the developers of the system document their understanding of the system. Design generates the blue print of the system that is to be implemented. The first step in creating an object oriented design is the identification of classes and their relationships.

  72. Question 44. Explain About A Class?

    Answer :

    Class describes the nature of a particular thing. Structure and modularity is provided by a Class in object oriented programming environment. Characteristics of the class should be understandable by an ordinary non programmer and it should also convey the meaning of the problem statement to him. Class acts like a blue print.

  73. Question 45. Explain About Instance In Object Oriented Programming?

    Answer :

    Every class and an object have an instance. Instance of a particular object is created at runtime. Values defined for a particular object define its State. Instance of an object explains the relation ship between different elements.

  74. Question 46. Explain About Inheritance?

    Answer :

    Inheritance revolves around the concept of inheriting knowledge and class attributes from the parent class. In general sense a sub class tries to acquire characteristics from a parent class and they can also have their own characteristics. Inheritance forms an important concept in object oriented programming.

  75. Question 47. Explain About Multiple Inheritance?

    Answer :

    Inheritance involves inheriting characteristics from its parents also they can have their own characteristics. In multiple inheritance a class can have characteristics from multiple parents or classes. A sub class can have characteristics from multiple parents and still can have its own characteristics.

  76. Question 48. Explain About Encapsulation?

    Answer :

    Encapsulation passes the message without revealing the exact functional details of the class. It allows only the relevant information to the user without revealing the functional mechanism through which a particular class had functioned.

  77. Question 49. Explain About Abstraction?

    Answer :

    Abstraction simplifies a complex problem to a simpler problem by specifying and modeling the class to the relevant problem scenario. It simplifies the problem by giving the class its specific class of inheritance. Composition also helps in solving the problem to an extent.

  78. Question 50. Explain The Mechanism Of Composition?

    Answer :

    Composition helps to simplify a complex problem into an easier problem. It makes different classes and objects to interact with each other thus making the problem to be solved automatically. It interacts with the problem by making different classes and objects to send a message to each other.

  79. Question 51. Explain About Polymorphism?

    Answer :

    Polymorphism helps a sub class to behave like a parent class. When an object belonging to different data types respond to methods which have a same name, the only condition being that those methods should perform different function.

  80. Question 52. Explain About Overriding Polymorphism?

    Answer :

    Overriding polymorphism is known to occur when a data type can perform different functions. For example an addition operator can perform different functions such as addition, float addition etc. Overriding polymorphism is generally used in complex projects where the use of a parameter is more.

  81. Question 53. Explain About Object Oriented Databases?

    Answer :

    Object oriented databases are very popular such as relational database management systems. Object oriented databases systems use specific structure through which they extract data and they combine the data for a specific output. These DBMS use object oriented languages to make the process easier.

  82. Question 54. Explain About Parametric Polymorphism?

    Answer :

    Parametric polymorphism is supported by many object oriented languages and they are very important for object oriented techniques. In parametric polymorphism code is written without any specification for the type of data present. Hence it can be used any number of times.

  83. Question 55. What Are All The Languages Which Support Oop?

    Answer :

    There are several programming languages which are implementing OOP because of its close proximity to solve real life problems. Languages such as Python, Ruby, Ruby on rails, Perl, PHP, Coldfusion, etc use OOP. Still many languages prefer to use DOM based languages due to the ease in coding.

  84. Question 56. Explain About The Analysis Phase?

    Answer :

    The anlaysis or the object oriented analysis phase considers the system as a solution to a problem in its environment or domain. Developer concentrates on obtaining as much information as possible about the problem. Critical requirements needs to be identified.

  85. Question 57. Explain About Realistic Modeling?

    Answer :

    As we live in a world of objects, it logically follows that the object oriented approach models the real world accurately. The object oriented approach allows you to identify entities as objects having attributes and behavior.

  86. Question 58. Name The Different Creational Patterns In Oo Design?

    Answer :

    There are three patterns of design out of which Creational patterns play an important role the various patterns described underneath this are: –
    1) Factory pattern
    2) Single ton pattern
    3) Prototype pattern
    4) Abstract factory pattern
    5) Builder pattern.

  87. Question 59. Explain What A Method Is?

    Answer :

    A method will affect only a particular object to which it is specified. Methods are verbs meaning they define actions which a particular object will perform. It also defines various other characteristics of a particular object.

  88. Question 60. Explain The Usage Of Encapsulation?

    Answer :

    Encapsulation specifies the different classes which can use the members of an object. The main goal of encapsulation is to provide an interface to clients which decrease the dependency on those features and parts which are likely to change in future. This facilitates easy changes to the code and features.