Tableau Interview Questions & Answers

Criteria Tableau QlikView
Data integration Exceptional Good
Working with multidimensional data Very Good Good
Support for PowerPoint Available Not available
Visual Drilldown Good Very Good
Scalability Good Limited by RAM

Whenever we crate context filter

  • Tableau will create a temporary table for this particular filter set and other filters will be apply on context filter data like cascade parameters… suppose we have crated context filter on countries >> we have chosen country as USA and India
  • Tableau will create a temporary table for this two countries data and if you have any other filers >>other will be apply on this two countries data if we don’t have any context filter
  • Each and individual record will check for all filters
  • The context filter is not frequently changed by the user – if the filter is changed the database must recomputed and rewrite the temporary table, slowing performance.
  • When you set a dimension to context, Tableau crates a temporary table that will require a reload each time the view is initiated. For Excel, Access and text data sources, the temporary table created is in an Access table format. For SQL Server, My SQL and Oracle data sources, you must have permission to create a temporary table on your server. For multidimensional data source, or cubes, temporary tables are not crated, and context filters only defined which filters are independent and dependent.

Tableau offers five main products: Tableau Desktop, Tableau Server, Tableau Online, Tableau reader and Tableau Public.

Data visualization refers to the techniques used to communicate data or information by encoding it as visual objects (e.g. points, lines or bars) contained in graphics.

Whether your data is in an on-premise database, a database, a data warehouse, a cloud application or an Excel file, you can analyze it with Tableau. You can create views of your data and share it with colleagues, customers, and partners. You can use Tableau to blend it with other data. And you can keep your data up to date automatically.

Filter is nothing but it is restricted to unnecessary, it is showing exact data. Basically filters are 3 types.

  1. Quick filter
  2. Context filter
  3. Datasource filter

Suppose I have data like

Eid Ename Salary Dept
1.abc 2000 java
2.bbc 3000 .net
3.Krishna 2500 java
Madhu 300
5.Vamshi 3000 mainframes
1.abc 1000 testing
2.bbc 3000 tableau
3.krishna 5000.net
4.Madhu 7000 testing
vanshi 9000 tableau
1 abc 11000 Mainframes
2 bbc 13000testing
3 krishna 15000 java
4 Madhu 17000 .nte
5 vamshi 19000.net

Aggregation: to display aggregate data
Sum/avg salary by each individual employee
drag ename on columna and salary on rows we will get sum (salary) of each and individual employee
now change measure type as Avg

Choose salary option – choose measure types as “Avg”

Disaggregation: To display each and every transaction

When you look at the aggregated data in the views above, each bar represents all transactions for a specific employee summed up or averaged into a single value. Now say that you want to see the individual salary transactions for each employee. You can create a view like that by selecting Analysis>Aggregate Measures.

Right click filter>>customize>>uncheck show all option

Yes!
Ex. In data source I have column like
empID, EmpName, EmpDept,EmpDsignation, EmpSalary
In reports I am using empname on columns and empsalry on rows.
I can use empDesignation on Filters

Extract can be used anywhere without any connection and you can build your own visualizations without connecting to Database.

I have 5 different excel files (2007.xls, 2008.xls..2011.xls) with same fields (film name, genre, budge, rating, profitability) but with data from different year (2007 to 2011). Can someone tell me how can I combine the film name, genre and profitability so that I can see the visualization of 2007 to 2011 in a single chart?

We can join max 32 table, it’s not possible to combine more than 32 tables.

For Eg: your client is in Healthcare domain and using SQL Server as their database. In SQL server there may be many Tableau like Claims Tables, Rejected Claims Table, Customer Table. Now, client wants to know customer wise claims and customer wise rejected claims table using the joins. Join is a query that combines the data form 2 or more tables by making use of Join condition.

We can join max 32 table, it’s not possible to combine more then 32 tables.

In Tableau the joins can perform in 2 ways.

  1. By making use of common columns.
  2. By making use of common data types.

If we create joins on the fields in Tableau all the table names are suffixing with $. While performing the joins on multiple tables, always go with the les amount of data tables, so that we can improve the performance.

In Tableau the joins are divided into 2 types.

  1. Equi Join,
  2. Non Equi Join

Equi Join: in the join condition if we are using Equality”=”operator then such a kind of join called as Equi join.

Non Equi Join: in the join condition apart from the Equality”=”if we use any other operator like <,>,<=,>= and=! Then such a kind of joins are called as Non Equi Join

Equi Join is divided into 3 types

  1. Inner Join,
  2. Outer Join,
  3. Self – Join.

1.Inner Join: Inner join will loads the only matching records from the both tables. Inner join condition:
Tableaa.id = Tableb.id

2.Outer Join:
Again the outer join divided into 3 types.

  • Left Outer Join,
  • Right Outer Join,
  • Full Outer Join.

Left outer join: Displays the complete data from the left + matching records from the right table.

Condition: tablea.id(+)

Right Outer Join: displays the complete data from the right + matching records from the left.

Condition: tablea.id(+)=tableb.id

Full outer join: full outer join load the complete data from the left table and right table. Condition: Table A full outer join Table B ON tablea.id= tableb.id

3.Self-Join: if we are performing join to the same table itself such a kind of join called as self-join
Non Equi Join:

In the join condition if we are using the operators apart from the equality “=” then such a kind of joins are called as Non Equi join.

Data Blending in Tableau:

For ex: your client is same Healthcare Client. They are operating their services in Asia, Europe, NA and so on & the are maintaining Asia data in SQL, Europe Data in SQL Server and NA data in MY SQL.

Now, your client wants to analyze their business across the world in a single worksheet. So you can’t perform join here.

Now you have make use of Data Blending Concept.
Normally in the Tableau we can perform the analysis on the single data server. If we want to perform the analysis from the multiple data sources in a single sheet then we have to make use of a new concept called as data blending.

Data blending mix the data from the different data sources and allow the users to perform th analysis in a single sheet. Blending means mixing. If we are mixing the data sources then it is called as data blending.

Rules to perform the data blending

In order to perform data blending there are few rules.

  1. If we are performing the data blending on 2 data source these 2 data sources should have at least 1 common dimension.
  2. In that common dimension at least 1 value should match.

In Tableau we can perform the data blending in 2 ways.

  1. Automatic way
  2. Custom way
  3. Automatic way:In the automatic way Tableau automatically defines the relationship between the 2 data sources based on the common dimensions and based on the matching values and the relationship is indicated with Orange color.
  4. Custom or Manual way:In the manual or custom way the user need to define the relationship manually.

Data blending fuctionality

  1. All the primary data sources and the secondary data sources are linked by specific relationship
  2. While performing the data blending each work sheet has a primary connection and optionally it might contains several secondary connections.
  3. All the primary connections are indicated in the Blue in the work sheet and all the secondary data sources indicated with the Orange color tick mark.
  4. In the data blending 1 sheet contains 1 primary data source and 1 sheet can contain end number of secondary data sources.

Dimensions is nothing but the descriptive text columns and facts are nothing but measures (numerical values) dimentionex:productname city..facts:sales, profit

A heat map is a great way to compare categories using color and size. In this, you can compare two different measures. Tree map is a very powerful visualization, particularly for illustrating hierarchical (tree – structured) data and part – to – whole relationships.

Twb is a live connection, it points to the data source; the user receiving twb needs permission to said data source and no data is included. .twbx takes data offline, stroes the data as a package or zip like file, thereby eradicating the need for permissions from end user, it’s now a snapshot in time of the data as of the time it was Saved as . twbx

To display two measure in one graph

Related Article: How To Use Tab admin For Administrative Task Automation In Tableau?

Multiple Measures are shown in single axis and also all the marks shown in single pane

  • Drag a dimension in a column
  • Drag the first measure in column
  • Drag 2nd measure in existing axis
  • Us/multiplemeasures_blendedaxes.html

In my view, Tableau stands out for several reasons:

First, most of the BI tools out there are pricey. However, Tableau has a free offering (Tableau Public) as well as a very popular (also free) academic distribution. Tableau is well recognized by firms like Forrester research to be one of the most easy to use, and agile products currently available. see here: Tableau Ranks #1 in The Forrester Wave: Advanced Data Visualization (ADV) Platforms That makes it easy to pick up and try new things with, which data visualization people love about it.

On the other hand, unlike some of the other BI tools, Tableau is not a complete technology stack, it is most useful for visualization and analytics. – you will need other products in addition to tableau for heavier enterprise data ETL, maintenance, and storage, etc. https://www.tableau.com/about/blog/2012/7/tableau-ranks-1-forrester-wave-advanced-data-visualization-adv-platforms-1852

You can’t test in Tableau as far as I know. It is a data visualization software.

Tableau currently not support the multi-valued parameters… “Case Study: The “dynamic parameter with a blend” technique can be used to highlight a single value, but not multiple values because of the way it works. As Tableau parameters are not dynamic, we cannot “filter” the list of values at runtime.”

We can use parameters with filters, calculated fields ,actions, measure-swap, changing views and auto updates

Custom SQL Query written after connecting to data for pulling the data in a structured view, One simple example is you have 50 columns in a table, but we need just 10 columns only. So instead of taking 50 columns you can write a sql query. Performance will increase.

Tableau provides easy to use, best in class, Visual Analytic capabilities, but it does not help with the plumbing (data foundation). You could, for example, marry SQL Server with Tableau to get the complete package. Tableau licenses are relatively expensive if you are looking to scale.

Traditional BI can handle it all but with significant upfront costs. Higher consulting, hardware and software costs. Among the mega-vendors, only Microsoft can provide a reasonable value proposition. Open source vendors like Pentaho and JasperSoft do not have an abundant enough talent pool, yet.

Palantir and Tableau are very different. Palantir has its roots in large data computer science problems involving security, payments, fraud detection and the likes. Customers/Investors include Paypal, CIA and others.

Tableau is a visualization player – with roots in Stanford U research. It’s Visual Query Language (VizQL) allows users to build visualizations on top of standard data warehouses or spreadsheets.

I have filterl and filter2..Based on filterl I need to filter2 data
Ex: Filterl as Country and Filter 2: States

I have chosen country as INDIA and filter2 should display only INDIA states
Choose options of Filter2 states :
select option of “Only relevant values “

Yes for sure! It gives you data insight to the extend that others don’t. Helps u plan and point the anomalies and improvise your process for betterment.

Using filters or calculated fields we can able to display the top 5 and last 5 sales in same view?

Generate the Map using cities –>then Drag the Profit and sales to the Details–>Add the state as Quick filter

If you want to show the Sales and profit in each and every city under the states in the same work sheet. According to your question you should have State, City, Sales and Profit filed in your dataset.

  1. Double click on the State filed.
  2. Drag the City and drop into Marks card (under the State fied)
  3. Drag the sales and drop into size.
  4. Drag the profit and drop into color.
  5. Click on Size legend and increase the size.(75%)
  6. Right click on the State field and select show quick filter.
  7. Select any state and check whether you got the required view or not. In this view size indicates the amount of sales and color indicates the Profit values.

Create Custom Color code in “Preferences.tps”
Navigation ::: Documents » My Table Repository »Preferences.tps
Add custom color code
Note: In tableau 9.0 version we have color picker option..

onnect data two times, one for database tables and one for flat file. The Data->Edit Relationships
Give a join condition on common column from db tables to flat file

Suppose I have data like
Eid Ename Salary Dept
1. abc 2000 java
2.bbc 3000 .net
3.Krishna 2500 java
Madhu 300
5.Vamshi 3000 mainframes
1.abc 1000 testing
2.bbc 3000 tableau
3.krishna 5000.net
4.Madhu 7000 testing
vamshi 9000 tableau
1 abc 11000 Mainframes
2 bbc 13000testing
3 krishna 15000 java
4 Madhu 17000 .nte
5 vamshi 19000.net

Aggregation: to display aggregate data

Sum/avg salary by each individual employee
drag ename on columna and salary on rows we will get sum (salary) of each and individual employee
now change measure type as Avg
Choose salary option – choose measure types as “Avg”

Disaggregation: To display each and every transaction

When you look at the aggregated data in the views above, each bar represents all transactions for a specific employee summed up or averaged into a single value. Now say that you want to see the individual salary transactions for each employee. You can create a view like that by selecting Analysis>Aggregate Measures.

Our goal is to help people see and understand data. Our software products put the power of data into the hands of everyday people, allowing a broad population of business users to engage with their data, ask questions, solve problems and create value.

Tableau Public is a free service that lets anyone publish interactive data to the web. Once on the web, anyone can interact with the data, download it, or create their own visualizations of it. No programming skills are required. Be sure to look at the gallery to see some of the things people have been doing with it.

Data modelling is the analysis of data objects that are used in a business or other context and the identification of the relationships among these data objects. Data modelling is a first step in doing object-oriented programming

I think we all work on different projects using Tableau, so the work begins from understanding the requirement getting the required data, story boarding then creating visualizations in tableau and then presenting it to the client for review.

Parameters are dynamic values that can replace constant values in calculations and can serve as filters

Tableau Performance is based on Data source performance. If data source takes more time to execute a query then Tableau must wait up to that time.

First create a schedule for particular time and then create extract for the data source and publish the workbook for the server. Before you publish, there is a option called Scheduling and Authentication, click on that and select the schedule from the drop down which is created and publish. Also publish data source and assign the schedule. This schedule will automatically run for the assigned time and the workbook is refreshed.

Parameters are dynamic values that can replace constant values in calculations and can serve as filters.Filters are used to restrict the data based on the condition u have mentioned in the filters shelf.

The Tableau Desktop Log files are located in C:UsersMyDocumentsMy Tableau Repository. If you have a live connection to the data source, check the log.txt and tabprotosrv.txt files. If you are using an extract, check the tdeserver.txt file. The tabprotosrv.txt file often shows detailed information about queries.

page shelf is power full part of tableau That you can use to controle the display of output as well as printed results of output.

  1. New visualizations are introduced like treemap, bubble chart and box and whisker plot
  2. We can copy worksheet directly from one workbook to another workbook
  3. Introduced R script
  • Step 1: Build a Map View Double-click a geographic fields such as State, Area Code, Zip Code, etc.
  • Step 2: Select the Fille Map Mark Type The Automatic mark type will show this type of view as circles over a map. On the Marks card, select Filled Map to color the geographic areas.
  • Step 3:Drag a Field to the Color Shelf Define how the locations are colored by dragging another field to the Color shelf.

Yes it may have its own drop down list, the entries which you make in the Parameter while creating it can be viewed as Dropdown list.

After creation of Dashboards if we get problem from sql side that means Custom Sql ….How to Rectify the sql performance from custom sql.

If your server license expires today, your user name on the server will have the role ‘unlicensed’ which means you cannot access, but others can. The Site Admin can ‘Change Ownership’ to another person, so extracts if enabled do not fail.

Here is the example of refreshing dashboard in every 3 seconds, Replace apisrc and server url with yours. The interval below is for 3 seconds.
Tableau JavaScript API

Tableau Desktop is based on breakthrough technology from Stanford University that lets you drag &amp; drop to analyze data. It is great data visualization tool, you can connect to data in a few clicks, then visualize and crate interactive dashboards with a few more.

You could talk feature – functionality for days, but at a high level there are four major differences.

  1. Speed:How fast can you get up and running with the system, answer questions, design and share dashboards and then change them? This is Where systems like Tableau and GoodData are far better than old – school business intelligence like Business Objects or Cognos. Traditional systems took months or years to intelligence like Business Objects or Cognos. Traditional systems took months or years to implement, with costs running to millions. Tableau has a free trail that installs in minutes and GoodData is cloud – based, so they are faster to implement by orders of magnitude. They are also faster to results: traditional BI requires IT and developers to make any changes to reports, so business users are struck in a queue waiting to get anything done. Tableau and GoodData provide more of a self – service experience.
  2. Analysis layer:This is where Tableau excels. It has a powerful and flexible drag & drop visualization engine based on some technology from Stanford. GoodData and traditional BI typically provide some canned reports but changing them requires significant time and money.
  3. Data layer:This is where the three options are most different:
    • GoodData requires you to move your data to its cloud. Traditional BI typically requires you to move your data to its data warehouse Tableau connects to a variety of existing data source and also provides a fast in – memory data engine, essentially a local database. Since most enterprises have their data stored all over the place, this provides the most choice and lets companies use the investment they’ve already made.
  4. Enterprise readiness: Traditional BI and Tableau do well here, with enterprise – level security and high scalability.

Tableau is business intelligence software that allows anyone to easily connect to data, then visualize and create interactive, sharable dashboards. It’s easy enough that any Excel user can learn it, but powerful enough to satisfy even the most complex analytical problems. Securely sharing your findings with others only takes seconds.

Tableau Server is browser- and mobile-based insight anyone can use. Publish dashboards with Tableau Desktop and share them throughout your organization. It’s easy to set up and even easier to run.

R is a popular open-source environment for statistical analysis. Tableau Desktop can now connect to R through calculated fields and take advantage of R functions, libraries, and packages and even saved models. These calculations dynamically invoke the R engine and pass values to R via the Rserve package, and are returned back to Tableau.

  1. Tableau Server can also be configured to connect to an instance of Rserve through the tabadmin utility, allowing anyone to view a dashboard containing R functionality.
  2. Combining R with Tableau gives you the ability to bring deep statistical analysis into a drag-and-drop visual analytics

Quick filter is used to view the filtering options and can be used to select the option. Normal filer is something you can limit the options from the list or use some conditions to limit the data by field or value.