MSBI Interview questions & material

What is SQL Server Integration Services (SSIS)?

  • SQL Server Integration Services (SSIS) is component of SQL Server 2005 and later versions. SSIS is an enterprise scale ETL (Extraction, Transformation and Load) tool which allows you to develop data integration and workflow solutions. Apart from data integration, SSIS can be used to define workflows to automate updating multi-dimensional cubes and automating maintenance tasks for SQL Server databases.

How does SSIS differ from DTS?

  • SSIS is a successor to DTS (Data Transformation Services) and has been completely re-written from scratch to overcome the limitations of DTS which was available in SQL Server 2000 and earlier versions. A significant improvement is the segregation of the control/work flow from the data flow and the ability to use a buffer/memory oriented architecture for data flows and transformations which improve performance.

What is the Control Flow?

  • When you start working with SSIS, you first create a package which is nothing but a collection of tasks or package components.  The control flow allows you to order the workflow, so you can ensure tasks/components get executed in the appropriate order.

What is the Data Flow Engine?

  • The Data Flow Engine, also called the SSIS pipeline engine, is responsible for managing the flow of data from the source to the destination and performing transformations (lookups, data cleansing etc.).  Data flow uses memory oriented architecture, called buffers, during the data flow and transformations which allows it to execute extremely fast. This means the SSIS pipeline engine pulls data from the source, stores it in buffers (in-memory), does the requested transformations in the buffers and writes to the destination. The benefit is that it provides the fastest transformation as it happens in memory and we don't need to stage the data for transformations in most cases.

What is a Transformation?

  •  A transformation simply means bringing in the data in a desired format. For example you are pulling data from the source and want to ensure only distinct records are written to the destination, so duplicates are  removed.  Anther example is if you have master/reference data and want to pull only related data from the source and hence you need some sort of lookup. There are around 30 transformation tasks available and this can be extended further with custom built tasks if needed.

 What is a Task?

  • A task is very much like a method of any programming language which represents or carries out an individual unit of work. There are broadly two categories of tasks in SSIS, Control Flow tasks and Database Maintenance tasks. All Control Flow tasks are operational in nature except Data Flow tasks. Although there are around 30 control flow tasks which you can use in your package you can also develop your own custom tasks with your choice of .NET programming language.

What is a Precedence Constraint and what types of Precedence Constraint are there?

  • SSIS allows you to place as many as tasks you want to be placed in control flow. You can connect all these tasks using connectors called Precedence Constraints. Precedence Constraints allow you to define the logical sequence of tasks in the order they should be executed. You can also specify a condition to be evaluated before the next task in the flow is executed.
  • These are the types of precedence constraints and the condition could be either a constraint, an expression or both 
    • Success (next task will be executed only when the last task completed successfully) or
    • Failure (next task will be executed only when the last task failed) or
    • Complete (next task will be executed no matter the last task was completed or failed).

What is a container and how many types of containers are there?

  • A container is a logical grouping of tasks which allows you to manage the scope of the tasks together.
  • These are the types of containers in SSIS:
    • Sequence Container - Used for grouping logically related tasks together
    • For Loop Container - Used when you want to have repeating flow in package
    • For Each Loop Container - Used for enumerating each object in a collection; for example a record set or a list of files.
  • Apart from the above mentioned containers, there is one more container called the Task Host Container which is not visible from the IDE, but every task is contained in it (the default container for all the tasks).

What are variables and what is variable scope?

  • A variable is used to store values. There are basically two types of variables, System Variable (like ErrorCode, ErrorDescription, PackageName etc) whose values you can use but cannot change and User Variable which you create, assign values and read as needed. A variable can hold a value of the data type you have chosen when you defined the variable.
  • Variables can have a different scope depending on where it was defined. For example you can have package level variables which are accessible to all the tasks in the package and there could also be container level variables which are accessible only to those tasks that are within the container.
What are data regions?

Data regions are report items that display repeated rows of summarized information from datasets.

You want to generate a report that is formatted as a chart. Can you use the Report Wizard to create such a report?

No, the Report Wizard lets you create only tabular and matrix reports. you must create the chart report directly by using the Report Designer.

You want to use BIDS to deploy a report to a different server than the one you chose in the Report Wizard. How can you change the server URL?

You can right-click the project in Solution Explorer and then change the Target-Server URL property.

What are the three SSRS command-line utilities and their primary functions?

RSConfig.exe is used to define the connection properties from the SSRS instance to the Report Server database; RSKeyMgmt.exe performs encryption key operations and scale-out deployment setup; RS.exe runs Report Server Script files that can perform report deployment and management operations.

Can you always create a cache of a report?

No, you can create a cache of a report only when certain requirements, such as having credentials stored in the Report Server, are met.

Can you edit the .rdl code associated with a linked report?

No, because a linked report has no .rdl code of its own. It refers to the .rdl code of the base report

What is Analysis Services

1.Microsoft SQL Server 2012 Analysis Services (SSAS) delivers online analytical processing (OLAP) and data mining functionality for business intelligence applications. 
2.Analysis Services supports OLAP by letting we design, create, and manage multidimensional structures that contain data aggregated from other data sources, such as relational databases. 
3.For data mining applications, Analysis Services lets we design, create, and visualize data mining models that are constructed from other data sources by using a wide variety of industry-standar data mining algorithms

 What are the features of Analysis Services

1.Ease of use with a lot of wizards and designers.
2.Flexible data model creation and management
3.Scalable architecture to handle OLAP
4.Provides integration of administration tools, data sources, security, caching,    and reporting etc.

5.Provides extensive support for custom applications

What is the need for SSAS 2012 component?

1.Analysis Services is the only component in SQL Server using which we can perform Analysis and Forecast operations
2.Faster Analysis and Troubleshooting.
3.Ability to create and manage Data warehouses
4.Apply efficient Security Principles

What languages are used in SSAS 2012

1.Structured Query Language (SQL)
2.Multidimensional Expressions (MDX) - an industry standard query language orientated towards analysis
3.Data Mining Extensions (DMX) - an industry standard query language oriented toward data mining.
4.Analysis Services Scripting Language (ASSL) - used to manage Analysis Services database objects

What is the difference between a derived measure and a calculated measure? 

1.       The difference between a derived measure and a calculated measure is when the calculation is performed. 

2.       A derived measure is calculated before aggregations are created, and the values of the derived measure are stored in the cube. 

3.       A calculated measure is calculated after aggregations are created, and the values of a calculated measure aren’t stored in the cube. 

4.       The primary criterion for choosing between a derived measure and a calculated measure is not efficiency, but accuracy

What is FASMI ?

A database is called a OLAP Database if the database satisfies the FASMI rules 

1.       Fast Analysis– is defined in the OLAP scenario in five seconds or less.

  1. Shared – Must support access  to data by many users in  the factors of Sensitivity and Write Backs.
  2. Multidimensional – The data inside the OLAP Database must be multidimensional in structure.  
  3. Information – The OLAP database Must support large volumes of data.

What is a partition? 

  1.     A  partition in Analysis Services is the physical location of stored cube data. 
  2.    Every cube has at least one partition by default. Each time we create a measure group, another partition is created. 
  3.   Queries run faster against a partitioned cube because Analysis Services only needs to read data from the partitions that contain the answers to the queries. 
  4.    Queries run even faster when partition also stores aggregations, the pre calculated totals for additive measures. Partitions are a powerful and flexible means of managing cubes, especially large cubes

What are the roles of an Analysis Services Information Worker?

      The role of an Analysis Services information worker is the traditional "domain expert" role in business intelligence (BI) someone who understands the data employed by a solution and is able to translate the data into business information.The role of an Analysis Services information worker often has one of the following job titles: Business Analyst (Report Consumer), Manager (Report Consumer), Technical Trainer, Help Desk/Operation, or Network Administrator

Explain the TWO-Tier Architecture of SSAS?  

  1.   SSAS uses both server and client components to supply OLAP and data mining functionality BI Applications.
  2.   The server component is implemented as a Microsoft Windows service. Each instance of Analysis Services implemented as a separate instance of the Windows service.
  3.   Clients communicate with Analysis Services using the standard the XMLA (XML For Analysis) , protocol for issuing commands and receiving responses, exposed as a web service  

How many types of dimension are possible in SSAS?

  1.    Bill of Materials
  2.    Currency
  3.    Channel
  4.    Customer
  5.    Geography
  6.    Organizations
  7.    Products
  8.    promotion
  9.    Regular
  10.    Scenario
  11.    Time
  12.     Unary
  13.    Accounts

 

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