In Analysis Services, a KPI is a collection of calculations that are associated with a measure group in a cube that are used to evaluate business success. We use KPI to see the business at the particular point, this is represents with some graphical items such as traffic signals,ganze etc
What are actions, how many types of actions are there, explain with example?
Actions are powerful way of extending the value of SSAS cubes for the end user. They can click on a cube or portion of a cube to start an application with the selected item as a parameter, or to retrieve information about the selected item.
One of the objects supported by a SQL Server Analysis Services cube is the action. An action is an event that a user can initiate when accessing cube data. The event can take a number of forms. For example, a user might be able to view a Reporting Services report, open a Web page, or drill through to detailed information related to the cube data
Analysis Services supports three types of actions..
Report action: Report action Returns a Reporting Services report that is associated with the cube data on which the action is based.
Drill through: Drillthrough Returns a result set that provides detailed information related to the cube data on which the action is based.
Standard: Standard has five action subtypes that are based on the specified cube data.
Dataset: Returns a mutlidimensional dataset.
Proprietary: Returns a string that can be interpreted by a client application.
Rowset: Returns a tabular rowset.
Statement: Returns a command string that can be run by a client application.
URL: Returns a URL that can be opened by a client application, usually a browser.
What is partition, how will you implement it?
You can use the Partition Wizard to define partitions for a measure group in a cube. By default, a single partition is defined for each measure group in a cube. Access and processing performance, however, can degrade for large partitions. By creating multiple partitions, each containing a portion of the data for a measure group, you can improve the access and processing performance for that measure group.
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What is the minimum and maximum number of partitions required for a measure group?
In 2005 a MAX of 2000 partitions can be created per measure group and that limit is lifted in later versions.
In any version the MINIMUM is ONE Partition per measure group.
What are confirmed dimensions, junk dimension and degenerated dimensions?
Confirm dimension: It is the dimension which is sharable across the multiple facts or data model. This is also called as Role Playing Dimensions.
junk dimension: A number of very small dimensions might be lumped (a small irregularly shaped) together to form a single dimension, a junk dimension – the attributes are not closely related. Grouping of Random flags and text Attributes in a dimension and moving them to a separate sub dimension is known as junk dimension.
Degenerated dimension: In this degenerate dimension contains their values in fact table and the dimension id not available in dimension table. Degenerated Dimension is a dimension key without corresponding dimension.
Example: In the PointOfSale Transaction Fact table, we have:
Date Key (FK), Product Key (FK), Store Key (FK), Promotion Key (FP), and POS Transaction Number
Date Dimension corresponds to Date Key, Production Dimension corresponds to Production Key. In a traditional parent-child database, POS Transactional Number would be the key to the transaction header record that contains all the info valid for the transaction as a whole, such as the transaction date and store identifier. But in this dimensional model, we have already extracted this info into other dimension. Therefore, POS Transaction Number looks like a dimension key in the fact table but does not have the corresponding dimension table.
What are the types of database schema?
They are 3 types of database schema they are
Star
Snowflake
Starflake
What are the difference between data mart and data warehouse?
Datawarehouse is complete data where as Data mart is Subset of the same.
Ex:
All the organisation data may related to finance department, HR, banking dept are stored in data warehouse where as in data mart only finance data or HR department data will be stored. So data warehouse is a collection of different data marts.
Have you ever worked on performance tuning, if yes what are the steps involved in it?
We need to identify the bottlenecks to tune the performance, to overcome the bottleneck we need to following the following.
Avoid named queries
Unnecessary relationships between tables
Proper attribute relationships to be given
Proper aggregation design
Proper partitioning of data
Proper dimension usage design
Avoid unnecessary many to many relationships
Avoid unnecessary measures
Set AttributeHierarchyEnabled = FALSE to Attributes that is not required
Won’t take even single measure which is not necessary.
What are the difficulties faced in cube development?
This question is either to test whether you are really experienced or when he doesnot have any questions to ask ..
You can tell any area where you feel difficult to work. But always the best answers will be the following.
Giving attribute relationships
Calculations
Giving dimension usage (many to many relationship)
Analyzing the requirements
Explain the flow of creating a cube?
Steps to create a cube in ssas
Create a data source.
Create a datasource view.
Create Dimensions
Create a cube.
Deploy and Process the cube.
What is a datasource or DS?
The data source is the Physical Connection information that analysis service uses to connect to the database that host the data. The data source contains the connection string which specifies the server and the database hosting the data as well as any necessary authentication credentials.
What is datasourceview or DSV?
A data source view is a persistent set of tables from a data source that supply the data for a particular cube. BIDS also includes a wizard for creating data source views, which you can invoke by right-clicking on the Data Source Views folder in Solution Explorer.
Datasource view is the logical view of the data in the data source.
Data source view is the only thing a cube can see.
What is named calculation?
A named calculation is a SQL expression represented as a calculated column. This expression appears and behaves as a column in the table. A named calculation lets you extend the relational schema of existing tables or views in a data source view without modifying the tables or views in the underlying data source.
Named calculation is used to create a new column in the DSV using hard coded values or by using existing columns or even with both.