What is the difference between Traditional BI Tools and Tableau?
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Traditional
BI Tools vs Tableau
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Traditional BI Tools
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Tableau
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1. Architecture
has hardware limitations.
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1. Do not have
dependencies.
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2. Based on
a complex set of technologies.
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2. Based on
Associative Search which makes it dynamic and fast
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3. Do not support
in-memory, multi-thread, multi-core computing.
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3. Supports
in memory when used with advanced technologies.
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4. Has a
predefined view of data.
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4. Uses
predictive analysis for various business operations.
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2. What is Tableau?
- Tableau
is a business intelligence software.
- It
allows anyone to connect to the respective data.
- Visualizes
and creates interactive, shareable dashboards.
3. What are the different Tableau Products and what is the latest
version of Tableau?
Here is the Tableau
Product family.
(i)Tableau Desktop:
It is a self service business analytics and data visualization that
anyone can use. It translates pictures of data into optimized queries. With
tableau desktop, you can directly connect to data from your data warehouse for
live upto date data analysis. You can also perform queries without writing a
single line of code. Import all your data into Tableau’s data engine from
multiple sources & integrate altogether by combining multiple views in a
interactive dashboard.
(ii)Tableau Server:
It is more of an enterprise level Tableau software. You can publish
dashboards with Tableau Desktop and share them throughout the organization with
web-based Tableau server. It leverages fast databases through live connections.
(iii)Tableau Online:
This is a hosted version of Tableau server which helps makes business
intelligence faster and easier than before. You can publish Tableau dashboards
with Tableau Desktop and share them with colleagues.
(iv)Tableau Reader:
It’s a free desktop application that enables you to open and view
visualizations that are built in Tableau Desktop. You can filter, drill down
data but you cannot edit or perform any kind of interactions.
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(v)Tableau Public:
This is a free Tableau software which you can use to make visualizations
with but you need to save your workbook or worksheets in the Tableau Server
which can be viewed by anyone.
4. What are the different datatypes in Tableau?
Tableau supports
the following data-types:
5. What are Measures and Dimensions?
Measures are 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.
Dimensions are 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.
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6. What is the difference between .twb and .twbx extension?
- 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.
7. What are the different types of joins in Tableau?
The joins in
Tableau are same as SQL joins. Take a look at the diagram below to understand
it.
8. How many maximum tables can you join in Tableau?
You can join a
maximum of 32 tables in Tableau.
9. What are the different connections you can make with your dataset?
We can either connect live to our data set or extract data onto Tableau.
- 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.
The benefit of Tableau extract over live connection is that extract can
be used anywhere without any connection and you can build your own
visualization without connecting to database.
10. What are shelves?
They are Named areas to the left and top of the view. You build views by
placing fields onto the shelves. Some shelves are available only when you
select certain mark types.
11. What are sets?
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.
12. What are groups?
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.
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13. What is a hierarchical field?
A hierarchical field in tableau is used for drilling down data. It means
viewing your data in a more granular level.
14. What is Tableau Data Server?
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.
Intermediate Level Tableau Interview Questions
15. What is Tableau Data Engine?
Tableau Data Engine is a really cool feature in Tableau. 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.
16. What are the different filters in Tableau and how are they different
from each other?
In Tableau, filters are used to restrict the data from database.
The different filters in Tableau are: Quick , Context and
Normal/Traditional filter are:
- 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.
- 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.
- 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.
17. How to create a calculated field in 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.
Take a look at the
example below:
18. What is a dual axis?
Dual Axis is an excellent phenomenon supported by Tableau that helps
users view two scales of two measures in the same graph. Many websites like
Indeed.com and other make use of dual axis to show the comparison between two
measures and their growth rate in a septic set of years. Dual axes let you
compare multiple measures at once, having two independent axes layered on top
of one another. This is how it looks like:
19. What is the difference between a tree map and heat map?
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.
20. What is disaggregation and aggregation of data?
The process of viewing numeric values or measures at higher and more
summarized levels of the data is called aggregation. When you place a measure
on a shelf, Tableau automatically aggregates the data, usually by summing it.
You can easily determine the aggregation applied to a field because the
function always appears in front of the field’s name when it is placed on a
shelf. For example, Sales becomes SUM(Sales). You can aggregate measures
using Tableau only for relational data sources. Multidimensional data sources
contain aggregated data only. In Tableau, multidimensional data sources are
supported only in Windows.
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According to Tableau, Disaggregating your data allows you to view every
row of the data source which can be useful when you are analyzing measures that
you may want to use both independently and dependently in the view. For
example, you may be analyzing the results from a product satisfaction survey
with the Age of participants along one axis. You can aggregate the Age field to
determine the average age of participants or disaggregate the data to determine
what age participants were most satisfied with the product.
21. What is the difference between joining and blending 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.
22. What are Extracts and Schedules in Tableau server?
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.
23. How to view underlying SQL Queries in Tableau?
Viewing underlying SQL Queries in Tableau provides two options:
- 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 Recording
Help -> Setting and Performance -> Stop Performance Recording.
- 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.
24. How to do Performance Testing in Tableau?
Performance testing is again an important part of implementing tableau.
This can be done by loading Testing Tableau Server with TabJolt, which is a
“Point and Run” load generator created to perform QA. While TabJolt is not
supported by tableau directly, it has to be installed using other open source
products.
25. Name the components of a Dashboard.
- Horizontal
– Horizontal
layout containers allow the designer to group worksheets and dashboard
components left to right across your page and edit the height of all
elements at once.
- Vertical
– Vertical
containers allow the user to group worksheets and dashboard components top
to bottom down your page and edit the width of all elements at once.
- Text
– All
textual fields.
- Image
Extract – A
Tableau workbook is in XML format. In order to extracts images, Tableau
applies some codes to extract an image which can be stored in XML.
- Web
[URL ACTION] – A
URL action is a hyperlink that points to a Web page, file, or other
web-based resource outside of Tableau. You can use URL actions to link to
more information about your data that may be hosted outside of your data
source. To make the link relevant to your data, you can substitute field
values of a selection into the URL as parameters.
26. How to remove ‘All’ options from a Tableau auto-filter?
The auto-filter provides a feature of removing ‘All’ options by simply
clicking the down arrow in the auto-filter heading. You can scroll down to
‘Customize’ in the dropdown and then uncheck the ‘Show “All” Value’ attribute.
It can be activated by checking the field again.
27. How to add Custom Color to Tableau?
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.
28. What is TDE file?
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.
29. Mention whether you can create relational joins in Tableau without
creating a new table?
Yes, one can
create relational joins in tableau without creating a new table.
30. How to automate reports?
You need to publish report to tableau server, while publishing you will
find one option to schedule reports.You just need to select the time when you
want to refresh data.
31. What is Assume referential integrity?
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.
32. Explain when would you use Joins
vs. Blending in Tableau?
If data resides in a single source, it is always desirable to use
Joins. When your data is not in one place blending is the most viable way
to create a left join like the connection between your primary and secondary
data sources.
33. What is default Data Blending
Join?
Data blending is
the ability to bring data from multiple data sources into one Tableau view,
without the need for any special coding. A default blend is equivalent to a
left outer join. However, by switching which data source is primary, or by
filtering nulls, it is possible to emulate left, right and inner joins.
34. What do you understand by blended
axis?
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.
35. What is story
in Tableau?
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.
36. What is the difference between
discrete and continuous in Tableau?
There are two types of data roles in Tableau – discrete and continuous
dimension.
- 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.
37.How to create stories in Tableau?
There are many ways to create story in Tableau. Each story point can be
based on a different view or dashboard, or the entire story can be based on the
same visualization, just seen at different stages, with different marks
filtered and annotations added. You can use stories to make a business case or
to simply narrate a sequence of events.
- 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.
38. What is the DRIVE Program Methodology?
Tableau Drive is a methodology for scaling out self-service analytics.
Drive is based on best practices from successful enterprise deployments. The
methodology relies on iterative, agile methods that are faster and more
effective than traditional long-cycle deployment.
A cornerstone of this approach is a new model of partnership between
business and IT.
39. How to use group in calculated
field?
By adding the same calculation to ‘Group By’ clause in SQL query or
creating a Calculated Field in the Data Window and using that field whenever
you want to group the fields.
- Using
groups in a calculation. You cannot reference ad-hoc groups in a
calculation.
- Blend
data using groups created in the secondary data source: Only calculated groups
can be used in data blending if the group was created in the secondary
data source.
- Use
a group in another workbook. You can easily replicate a group in
another workbook by copy and pasting a calculation.
40. Mention what is the difference
between published data sources and embedded data sources in Tableau?
The difference between published data source and embedded data source is
that,
- 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.
41.
Mention what are different Tableau files?
Different Tableau
files include:
- Workbooks: Workbooks hold one or
more worksheets and dashboards
- Bookmarks: It contains a single
worksheet and its an easy way to quickly share your work
- Packaged
Workbooks: It
contains a workbook along with any supporting local file data and
background images
- Data
Extraction Files: Extract files are a local copy of a
subset or entire data source
- Data
Connection Files: It’s a small XML file with various
connection information
Expert level Tableau Interview
Questions
42. How to embed views onto Webpages?
You can embed interactive Tableau views and dashboards into web pages,
blogs, wiki pages, web applications, and intranet portals. Embedded views
update as the underlying data changes, or as their workbooks are updated
on Tableau Server. Embedded views follow the same licensing and permission
restrictions used on Tableau Server. That is, to see a Tableau view that’s
embedded in a web page, the person accessing the view must also have an account
on Tableau Server.
Alternatively, if your organization uses a core-based license on Tableau
Server, a Guest account is available. This allows people in your organization
to view and interact with Tableau views embedded in web pages without having to
sign in to the server. Contact your server or site administrator to find out if
the Guest user is enabled for the site you publish to.
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.
43. Design a view in a map such that
if user selects any state, the cities under that state has to show profit and
sales.
According to your
question you must have state, city, profit and sales fields in your dataset.
Step 1: Double click
on the state field
Step 2: Drag the city
and drop it into Marks card.
Step 3: Drag the
sales and drop it into size.
Step 4: Drag profit
and drop it into color.
Step 5: Click on size
legend and increase the size.
Step 6: Right click
on state field and select show quick filter.
Step 7: Select
any state now and check the view.
44. Think that I am using Tableau
Desktop & have a live connection to Cloudera Hadoop data. I need to press
F5 to refresh the visualization. Is there anyway to automatically refresh
visualization every ‘x’ seconds instead of pressing F5?
Here is an example
of refreshing the dashboard for every 5 seconds.
All you need to do
is replace the api src and server url with yours.
<!DOCTYPE
html>
<html
lang="en">
<head>
<title>Tableau
JavaScript API </title>
<script
type="text/javascript"
src="http://servername/javascripts/api/tableau_v8.js"></script>
</head>
<div
id="tableau Viz"></div>
<script
type='text/javascript'>
var
placeholderDiv = document.getElementById("tableau Viz");
var
url = "http://servername/t/311/views/Mayorscreenv5/Mayorscreenv2";
var
options={
hideTabs:True,
width:"100%",
height:"1000px"
};
var
viz= new tableauSoftware.Viz(placeholderDiv,url,options);
setInterval
(function() {viz.refreshDataAsync()},5000);
</script>
</body>
</html>
Some Additional Tricky Tableau Interview Questions
45.
Suppose my license expires today, will users be able to view dashboards or
workbooks which I published in the server earlier?
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.
46. Is Tableau software good for
strategic acquisition?
Yes! For sure. It gives you data insight to the extent that other tools
can’t. Moreover, it also helps you to plan and point the anomalies and
improvise your process for betterment of your company.
47. Can we place an excel file in a
shared location and and use it to develop a report and refresh it in regular
intervals?
Yes, we can do it.
But for better performance we should use Extract.
48. Can Tableau be installed on
MacOS?
Yes, Tableau
Desktop can be installed on both on Mac and Windows Operating System.
49. What is the maximum no. of rows
Tableau can utilize at one time?
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.
50. When publishing workbooks on
Tableau online, sometimes a error about needing to extract appears. Why does it
happen occasionally?
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
