Tableau Interview Questions

Yes, we can do it. But for better performance we should use Extract.

Can we place an excel file in a shared location and and use it to develop a report and refresh it in regular intervals?

Bullet graph is a variant of Bar graph. It is responsible for comparing performance of one measure with other measures.

Define Bullet graph?

Gantt Chart displays the progress of a value over the period. It consists of bars along with time axis. It is a project management tool. Here, each bar is measure of a task in the project framework.

Define Gantt chart?

? Adding a Custom Color refers to a power tool in Tableau. Restart you Tableau desktop once you save .tps file. From the Measures pane, drag the one you want to add color to Color. From the color legend menu arrow, select Edit Colors. When a dialog box opens, select the palette drop-down list and customize as per requirement.

How do you add custom color to tableau?

-Click the drop down to the right of Dimensions on the Data pane and select "Create > Calculated Field" to open the calculation editor. -Name the new field and create a formula.

How do you create a calculate field?

-Click the New Story tab. -In the lower-left corner of the screen, choose a size for your story. Choose from one of the predefined sizes, or set a custom size, in pixels. -By default, your story gets its title from its sheet name. To edit it, double-click the title. You can also change your title's font, color, and alignment. Click Apply to view your changes. -To start building your story, drag a sheet from the Story tab on the left and drop it into the center of the view -Click Add a caption to summarize the story point. -To highlight a key takeaway for your viewers, drag a text object over to the story worksheet and type your comment. -To further highlight the main idea of this story point, you can change a filter or sort on a field in the view, then save your changes by clicking Update above the navigator box.

How do you create a story in Tableau?

? You can do the following to embed views and adjust their default appearance: Get the embed code provided with a view: The Share button at the top of each view includes embed code that you can copy and paste into your webpage. (The Share button doesn't appear in embedded views if you change the showShareOptions parameter to false in the code.) Customize the embed code: You can customize the embed code using parameters that control the toolbar, tabs, and more. For more information, see Parameters for Embed Code. Use the Tableau JavaScript API: Web developers can use Tableau JavaScript objects in web applications. To get access to the API, documentation, code examples, and the Tableau developer community, see the Tableau Developer Portal.

How do you embed views onto Webpages?

There are two options for viewing underlying SQL Queries in Tableau: 1. Create a Performance Recording to record performance information about the main events you interact with workbook. Users can view the performance metrics in a workbook created by Tableau.Help -> Settings and Performance -> Start Performance RecordingHelp -> Setting and Performance -> Stop Performance Recording. 2. Reviewing the Tableau Desktop Logs located at C:UsersMy DocumentsMy Tableau Repository. For live connection to data source, you can check log.txt and tabprotosrv.txt files. For an extract, check tdeserver.txt file.

How do you view underlying SQL Queries in Tableau?

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How many maximum tables can you join in Tableau?

-Use an Extract to make workbooks run faster -Reduce the scope of data to decrease the volume of data -Reduce number of marks on the view to avoid information overload -Try to use integers or Booleans in calculations as they are much faster than strings -Hide unused fields -Use Context filters -Reduce filter usage and use some alternative way to achieve same result -Use indexing in tables and use same fields for filtering -Remove unnecessary calculations and sheets

State some ways to improve performance of Tableau

If your server license expires today, your username on the server will have the role 'unlicensed' which means you cannot access but others can. The site admin can change the ownership to another person so that the extracts do not fail.

Suppose my license expires today, will users be able to view dashboards or workbooks which I published in the server earlier?

the descriptive attribute values for multiple dimensions of each attribute, defining multiple characteristics. A dimension table, having reference of a product key form the table, can consist of product name, product type, size, color, description, etc.

What are Dimensions?

- Data extracts are the first copies or subdivisions of the actual data from original data sources. The workbooks using data extracts instead of those using live DB connections are faster since the extracted data is imported in Tableau Engine.After this extraction of data, users can publish the workbook, which also publishes the extracts in Tableau Server. However, the workbook and extracts won't refresh unless users apply a scheduled refresh on the extract. -Scheduled Refreshes are the scheduling tasks set for data extract refresh so that they get refreshed automatically while publishing a workbook with data extract. This also removes the burden of republishing the workbook every time the concerned data gets updated.

What are Extracts and Schedules in Tableau server?

A .twb is an xml document which contains all the selections and layout made you have made in your Tableau workbook. It does not contain any data. A .twbx is a 'zipped' archive containing a .twb and any external files such as extracts and background images.

What is the difference between a .twb and .twbx extension?

the numeric metrics or measurable quantities of the data, which can be analyzed by dimension table. Measures are stored in a table that contain foreign keys referring uniquely to the associated dimension tables. The table supports data storage at atomic level and thus, allows more number of records to be inserted at one time. For instance, a Sales table can have product key, customer key, promotion key, items sold, referring to a specific event.

What are Measures?

A group is a combination of dimension members that make higher level categories. For example, if you are working with a view that shows average test scores by major, you may want to group certain majors together to create major categories.

What are groups?

Sets are custom fields that define a subset of data based on some conditions. A set can be based on a computed condition, for example, a set may contain customers with sales over a certain threshold. Computed sets update as your data changes. Alternatively, a set can be based on specific data point in your view.

What are sets?

1. Boolean 2. Date 3. Date & time 4. Geographical Values 5. Text/String 6. Number (decimal) 7. Number (whole)

What are the different datatypes in Tableau?

1. Normal Filter is used to restrict the data from database based on selected dimension or measure. A Traditional Filter can be created by simply dragging a field onto the 'Filters' shelf. 2. Quick filter is used to view the filtering options and filter each worksheet on a dashboard while changing the values dynamically (within the range defined) during the run time. 3. Context Filter is used to filter the data that is transferred to each individual worksheet. When a worksheet queries the data source, it creates a temporary, flat table that is uses to compute the chart. This temporary table includes all values that are not filtered out by either the Custom SQL or the Context Filter.

What are the different filters in Tableau and how are they different from each other?

1. Left Join 2. Right Join 3. Inner Join 4. Outer Join

What are the different types of joins in Tableau?

In Tableau, measures can share a single axis so that all the marks are shown in a single pane. Instead of adding rows and columns to the view, when you blend measures there is a single row or column and all of the values for each measure is shown along one continuous axis. We can blend multiple measures by simply dragging one measure or axis and dropping it onto an existing axis.

What do you understand by blended axis?

In some cases, you can improve query performance by selecting the option to Assume Referential Integrity from the Data menu. When you use this option, Tableau will include the joined table in the query only if it is specifically referenced by fields in the view.

What is Assume referential integrity?

Context Filters are applied to the data rows before any other filters. They are limited to views, but they can be applied on selected sheets. They define Aggregation and Disaggregation of data in Tableau Step 1: Drag the subcategory dimensions to the row shelf and the measure sales to the column shelf. Now choose the horizontal bar chart as chart type and again drag the sub category dimensions to the filter shelf. Then we will get the following chart. Step 2: Right-click on the Sub-Category field in the filter shelf and go the Top fourth tab. Choose the option field, from the next drop-down and choose the option Top 10 by Sales Sum as shown in the following screenshot. Step 3: Drag the dimension Category to the filter shelf. Give right-click on general tab to edit and under that choose Furniture from the list. As you can see the result shows three subcategories of products. Step 4: Right-click the Category: Furniture filter and select the option Add to Context. This produces the final result, which shows the subcategory of products from the category Furniture which are among the top 10 subcategories across all the products.

What is Context Filter and show the steps on how to create the Context Filter Tableau?

? TDE is a Tableau desktop file that contains a .tde extension. It refers to the file that contains data extracted from external sources like MS Excel, MS Access or CSV file.There are two aspects of TDE design that make them ideal for supporting analytics and data discovery. Firstly, TDE is a columnar store. The second is how they are structured which impacts how they are loaded into memory and used by Tableau. This is an important aspect of how TDEs are "architecture aware". Architecture-awareness means that TDEs use all parts of your computer memory, from RAM to hard disk, and put each part to work what best fits its characteristics.

What is TDE file?

Its an analytical database designed to achieve instant query response, predictive performance, integrate seamlessly into existing data infrastructure and is not limited to load entire data sets into memory. If you work with a large amount of data, it does takes some time to import, create indexes and sort data but after that everything speeds up. Tableau Data Engine is not really in-memory technology. The data is stored in disk after it is imported and the RAM is hardly utilized.

What is Tableau Data Engine?

Tableau server acts a middle man between Tableau users and the data. Tableau Data Server allows you to upload and share data extracts, preserve database connections, as well as reuse calculations and field metadata. This means any changes you make to the data-set, calculated fields, parameters, aliases, or definitions, can be saved and shared with others, allowing for a secure, centrally managed and standardized dataset. Additionally, you can leverage your server's resources to run queries on extracts without having to first transfer them to your local machine.

What is Tableau Data Server?

A hierarchical field in tableau is used for drilling down data. It means viewing your data in a more granular level.

What is a hierarchical field?

Parameters are dynamic values, we can replace the constant values in calculations.

What is a parameter Tableau? And how it works?

A story is a sheet that contains a sequence of worksheets or dashboards that work together to convey information. You can create stories to show how facts are connected, provide context, demonstrate how decisions relate to outcomes, or simply make a compelling case. Each individual sheet in a story is called a story point.

What is story in Tableau?

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

What is the benefit of Tableau extract over live connection?

Live: Connecting live to a data set leverages its computational processing and storage. New queries will go to the database and will be reflected as new or updated within the data. Extract: An extract will make a static snapshot of the data to be used by Tableau's data engine. The snapshot of the data can be refreshed on a recurring schedule as a whole or incrementally append data. One way to set up these schedules is via the Tableau server.

What is the difference between a live connection and an extract?

-A heat map can be used for comparing categories with color and size. With heat maps, you can compare two different measures together. -A tree map also does the same except it is considered a very powerful visualization as it can be used for illustrating hierarchical data and part-to-whole relationships.

What is the difference between a tree map and heat map?

-Discrete data roles are values that are counted as distinct and separate and can only take individual values within a range. Examples: number of threads in a sheet, customer name or row ID or State. Discrete values are shown as blue pills on the shelves and blue icons in the data window. -Continuous data roles are used to measure continuous data and can take on any value within a finite or infinite interval. Examples: unit price, time and profit or order quantity. Continuous variables behave in a similar way in that they can take on any value. Continuous values are shown as green pills.

What is the difference between discrete and continuous in Tableau?

-Joining term is used when you are combining data from the same source, for example, worksheet in an Excel file or tables in Oracle database -While blending requires two completely defined data sources in your report.

What is the difference between joining and blending in Tableau?

-Published data source: It contains connection information that is independent of any workbook and can be used by multiple workbooks. -Embedded data source: It contains connection information and is associated with a workbook.

What is the difference between published data sources and embedded data sources in Tableau?

Tableau is not restricted by the no. of rows in the table. Customers use Tableau to access petabytes of data because it only retrieves the rows and columns needed to answer your questions.

What is the maximum no. of rows Tableau can utilize at one time?

This happens when a user is trying to publish a workbook that is connected to an internal server or a file stored on a local drive, such as a SQL server that is within a company's network.

When publishing workbooks on Tableau online, sometimes a error about needing to extract appears. Why does it happen occasionally?