QlikView Interview question and answers
Question.1 What is QlikView?
- QlikView is an in-memory Business Intelligence application. In-memory means data is loaded and queried from RAM.
- QlikView uses the associative technology. Tables having common fields are associated or linked.
- QlikView stores data at a granular level. Data is not pre-aggregated.
- Components of QlikView are QlikView desktop and Server/Publisher and Access point.
- The developer uses QlikView desktop to write scripts. Scripts are used to extract data from the data source and design data model. QlikView desktop is also used to create dashboard/visualizations.
- Dashboards are deployed on the Server. Publisher, a component of server, helps in data load, data reduction and scheduling.
- Business users view Dashboards through Access point portal. The file extension of the QlikView design file is .qvw.
Question.2 What is Business Intelligence? How QlikView is a BI application?
- BI or Business Intelligence is a general term used to categorize software applications that help in analyzing and understanding data. Such applications enable business users in making useful decisions.
- These applications include functionalities such as ETL (Extract, transform and load) data and creating visualizations in terms of charts and tables.
- QlikView is a BI application because QlikView has a strong scripting engine that performs ETL. It can take the raw data, transform it and provide highly interactive visualization objects to help in executive decision making.
Question.3 Why QlikView is required in today’s business world?
Every business has tons of data. This data can be in different formats like database, excel, xml and so on.
- QlikView can connect to any data format.
- It can connect to different data formats such as excel and database table in on dashboarding application.
- QlikView can handle huge amounts of data.
- QlikView helps in extracting/transforming and interpreting this data.
- Using associative technology, QlikView automatically identifies the relationship between the data and presents in a format – charts/tables that is understandable to the users.
- It helps business in discovering data and making decisions.
Question.4 How association works in QlikView ?
- In QlikView, an association is formed between 2 tables based on common field names.
- There can be only one link between the tables, i.e. there can be only one common field between the tables.
- Synthetic key is formed, if more than one common field is present between the tables.
- The association helps in leading to the data directly, unlike other tools which
follow a predefined path.
Question.5 What data sources can be used with QlikView?
QlikView can connect to a variety of data sources. It can connect to Excel sheets, Text files, xml, web files, relational database or a data warehouse. QlikView can connect to these data sources in one design/Qvw file. It automatically identifies the relationship between the data based on the common field names.
Question.6 What is Access Point?
The access point is a portal through which users can access dashboards. Access point works with clients like AJAX or IE Plug-in. No installation is required for AJAX client.The IE plugin requires installation.
Question.7 What is QlikView Development life cycle?
The typical QlikView implementation follows:
- Requirement gathering. Discussion with users to understand data and visualization requirements.
- Analyze data sources. Gather information on different data sources and the relationships among the data elements.
- Create mock-ups of the dashboards. User review of mock-ups
- Create data model.
- Create dashboards
- Unit Testing.
- Review of dashboard by the users.
- Deploy dashboards over the Server.
- Create data load and dashboard distribution tasks.
- Publish dashboards to be viewed over access point.
Question.8 What are dimensions and facts? What is the cardinality between them?
Dimension and fact tables are used in describing a star schema.
- Dimension table contains the text attribute of the data. It provides the context to Fact table. Dimensions are used to filter the fact table.
- Fact table contains the measurable attribute of the data. Such as Revenue, Profit or Population.
- In a star schema, fact is in the center surrounded by different dimensions.
- The cardinality between Dimension and a fact table is one to Many, with Many on the fact side.
Question.9 Given an ER diagram, how you will identify fact and dimension tables?
- Cardinality between Dimension and Fact is one to many, with many on the Factside. Look for One to Many relationship in the ER diagram.
- Dimension contain the textual/ descriptive attribute and Fact contain the measured data. Look for such data elements in the tables.
- Fact table contains the foreign key of the dimension table.
Question.10 How requirement gathering is performed for a Dashboarding application?
- When creating a dashboard, it is important to get the requirements from the users. When
- Take data requirements. Data sources, key filters, data refresh frequency.
- Inquire users about the KPI’s (Key performance Indicators).
- Understand what questions users are trying to get from the data.
- Document business rules required for the dashboards.
- Understand security requirements.
- Gather details about any existing reports or desired visualization.
- Provide the look or screen layout of the dashboard charts and tables in excel or hand drawn. Get users’ feedback on the layout.
- Get requirements about the screen resolution.
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