Qlikview Interview Questions (Part-2)

11. What is Container ?

A : A container object can be used to hold multiple charts.  You can use a container object to put multiple charts in the same box. All charts will appear in the same window but only one chart will appear active at a given time. You can click the chart title to switch or toggle between charts. A word of advice: Use containers with caution. They form linked objects and might affect the properties of all linked objects.

12. What is Dimensions ( What is difference between Expression and Dimension)?

A : Each data warehouse consists of dimensions and measures. Dimensions allow data analysis from various perspectives. For example, time dimension could show you the breakdown of sales by year, quarter, month, day and hour. Product dimension could help you see which products bring in the most revenue. Supplier dimension could help you choose those business partners who always deliver their goods on time. Customer dimension could help you pick the strategic set of consumers to whom you’d like to extend your very special offers.

13. Explain about Normalized Data?

A : Well Structured Form of Data, which doesnt have any repetition or redundancy of data. Its a kind of Relational data. Its mainly used in OLTP kind of stuffs De-normalized Data – Its a whole bunch of data without any relationship among themselves, with redundancy of data. Its mainly used in OLAP kind of stuffs.

14. What is Snow-flaking Schema ?

A : Snowflake Schema : An extension of the star schema by means of applying additional dimensions to the Dimensions of a star schema in a relational environment. Snow-flaking is a form of dimensional modeling; dimensions are stored in multiple relational dimension tables.  A snowflake schema is a variation of the star schema. Snow-flaking is used to improve the performance of specific queries.  The schema is diagrammed with each fact surrounded by its associated dimensions as in a star schema, and those dimensions are further related to other dimensions, branching out into a snowflake pattern. 

15 . Explain QlikView Resident Load?

A : Create a new logical table in QlikView, based on a previously loaded (resident) table.

16. What is Apply Map (Mapping Tables)?

A :  Sometimes you need to add an extra field to a table to use a combination of fields from different tables, or you want to add a field to clean up the data structure. Qlik- View has an effective way to add single fields to a table called mapping tables.  syntax — mapping ( load statement | select statement ) applymap( ‘mapname’, expr, [ , defaultexpr ] )

17.What Is Star Schema ?

A : A star schema is the simplest form of dimensional model, in which data is organized into facts and dimensions.  A fact is an event that is counted or measured, such as a sale or login.  A dimension contains reference information about the fact, such as date, product, or customer. A star schema is diagrammed by surrounding each fact table with its associated dimensions table. The output diagram resembles a star.

Star Schema Definition : A means of aggregating data based on a set of known dimensions. It stores data multi-dimensionality in a two dimensional Relational Database Management System (RDBMS), such as Oracle.

18. What is Central Link Table?

A : In the event of multiple fact tables QlikView In-Memory Technology allows us to create a central link table that only contains the existing data combinations. Instead of Joining the tables the event dimensions can be merged (CONCATENATED) in to one central Link table. This link table can then be linked back to the event measures one side and the dimension tables on the other.

19. What is binary load ?

A : Binary load is loading data from another QV file.  For example, you have application A.qvw.  You can create another application B.qvw with script binary A.qvw. binary file  where:

file ::= [ path ] filename

Examples:

Binary customer.qvw;

Binary c:\qv\customer.qvw;

The path is the path to the file, either absolute, or relative to the .qvw file containing this script line.

20. What is a synthetic key?

A : It is a field that contains all possible combinations of common fields among tables.