What is Tableau?
Tableau is business intelligence software that allows anyone to easily connect to data, then visualize and create interactive, shareable dashboards. It is 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.
What is data visualization?
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.
Tableau uses VizQL (Visual query language).
What is VizQL ?
VizQL is a visual query language that translates drag-and-drop actions into data queries and then expresses that data visually. VizQL delivers dramatic gains in people’s ability to see and understand data by abstracting the underlying complexities of query and analysis. The result is an intuitive user experience that lets people answer questions as fast as they can think of them.
How Does Tableau Work?
While Tableau lets you analyze databases and spreadsheets like never before, you don’t need to know anything about databases to use Tableau. In fact, Tableau is designed to allow business people with no technical training to analyze their data efficiently. Tableau is based on three simple concepts:
Connect: Connect Tableau to any database that you want to analyze.
Note that Tableau does not import the data. Instead it queries to the database directly.
Analyze: Analyzing data means viewing it, filtering it, sorting it, performing calculations on it, reorganizing it, summarizing it, and so on. Using Tableau you can do all of these things by simply arranging fields of your data source on a Tableau worksheet. When you drop a field on a worksheet, Tableau queries the data using standard drivers and query languages (like SQL and MDX) and presents a visual analysis of the data.
Share: You can share results with others either by sharing workbooks with other Tableau users, by pasting results into applications such as Microsoft Office, printing to PDF or by using Tableau Server to publish or embed your views across your organization.
What are the other data visualization tools available in the market?
What are the different tableau products available?
oTableau Desktop
o Tableau Server
o Tableau online
o Taleau Public
o Tableau Mobile
o Tableau Reader
Which are all the data source systems that Tableau can connect?
Before you can build a view and analyze your data, you must first connect Tableau to your data. Tableau Desktop supports connecting to a wide variety of data, stored in a variety of places. For example, your data might be stored on your computer in a spreadsheet or a text file, or in a big data, relational, or cube (multidimensional) database on a server in your enterprise. Or, you might connect to public domain data available on the web such as U.S. Census Bureau information, or to a cloud database source, such as Google Analytics, Amazon Redshift, or Salesforce
Data Soucres
Excel, Text File, Access, JSON File, Spatial File, Statistical File, Other Files (such as Tableau .tde, .tds, .twbx), Tableau Server or Tableau Online, Actian Matrix, Actian Vector, Amazon Aurora, Amazon EMR, Amazon Redshift, Anaplan, Apache Drill, Aster Database, Cisco Information Server, Cloudera Hadoop, DataStax Enterprise, EXASolution, Firebird, Google Analytics, Google BigQuery, Google Cloud SQL, Google Sheets, Hortonworks Hadoop Hive, HP Vertica, IBM BigInsights, IBM DB2, IBM PDA (Netezza), Kognitio, MapR Hadoop Hive, Marketo, MarkLogic, MemSQL, Microsoft Analysis Services, Microsoft PowerPivot, Microsoft SQL Server, MonetDB, MySQL, OData, Oracle, Oracle Essbase, Pivotal Greenplum Database, PostgreSQL, Presto, Progress OpenEdge, QuickBooks Online, Salesforce, SAP HANA, SAP NetWeaver Business Warehouse, SAP Sybase ASE, SAP Sybase IQ, SharePoint Lists, Snowflake, Spark SQL,Splunk, Teradata, Teradata OLAP Connector, Web Data Connector and Other Databases (ODBC)
What are all the different data types available in Tableau?
All fields in a data source have a data type. The data type reflects the kind of information stored in that field, for example integers (410), dates (1/23/2015) and strings (“Wisconsin”). The data type of a field is identified in the Data pane by one of the icons shown below.
Data type icons in Tableau
Data type icons in Tableau
Icon
|
Data type
|
 |
Text (string) values
|
 |
Date values
|
 |
Date & Time values
|
 |
Numerical values
|
 |
Boolean values (relational only)
|
 |
Geographic values (used with maps)
|
You can change the data type for a field either on the Data Source page or in the Data pane
What is the difference between twb file and twbx file extension?
When to use which chart?
How many tables can be joined in tableau?
The maximum number of 32 tables can be joined in Tableau. A table size must also be limited to 255 columns (fields).
What are the different types of joins in Tableau?
In general, there are four types of joins that you can use to combine your data in Tableau: inner, left, right, and full outer. The tables you can join and the different join types you can use depend on the database or file you connect to. You can tell which join types your data supports by checking the join dialog after you've connected to your data and have at least two tables on the canvas.
What is the difference between twb file and twbx file extension?
Tableau Workbook File (TWB) is an XML document. It contains the information about your sheets, dashboards and stories. The TWB file references a data source file such as Excel or TDE, and when you save the TWB file, it is linked to the source.
The most important thing to remember about TWB files is that they don’t contain any data – if you want to share your workbook, therefore, you will need to send both the Tableau Workbook File and the data source file.
Tableau Packaged Workbook (TWBX) is a package of files “compressed” together. It includes a data source file, TWB, and any other file used to produce the workbook (including images).
TWBX is intended for sharing. It does not link to the original file source; instead it contains a copy of the data that was obtained when the file was created. TWBX files are usually used as reports and can be viewed using Tableau Viewer.
TWBX isn’t designed for auto updating. If you refresh/update the source file, TWBX will stay unchanged. If you want your workbook to update when the source file is updated, you need to use the TWB file format.
How to publish the workbook to Tableau server?
1. In Tableau Desktop, open the workbook you want to publish.
2. Go to Server Menu > Publish Workbook.
If the Publish Workbook option does not appear on the Server menu, make sure a worksheet or dashboard tab is active (not the Data Source tab).
3. Once you log into the server, select site and then select Project, Name and Desc
4. For Permissions, accept the default project settings.
Generally a site administrator manages permissions on the server.
For Data Sources, select Edit if you want to change the method for how people to access the underlying data your workbook connects to, or to change how the data is published (embedded in the workbook or published separately).
o If you’re publishing an extract, and you want to set up a refresh schedule, you must select Embed password or Allow refresh access, depending on whether your underlying data is on-premises or in the cloud.
o If your workbook connects to a Tableau data source, we recommend embedding the password. This is the default option if you are publishing one of the workbook’s connections separately. Selecting Prompt users requires additional permissions on the Tableau data source.
6. Configure other settings that are available for this workbook.
For more information, see Variable publishing options.
7. Click Publish.
8. (Optional) Set up a refresh schedule for each extract you published.
Below link provides detailed information.
What is data blending?
Data blending is the process of combining data from multiple sources into a functioning dataset.
What is the difference between join and blending?
In Tableau, Join is used to join the tables from same type of data source. In case of data blending, different data sources can be joined.
How can you schedule tableau data refresh?
Log into Tableau Server -> Click on Content - > Go to Data Sources -> Select Connection Name -> Select Refresh Schedule and assign appropriate schedule (In case if you do not have access to create new schedules, work with Tableau admin team to create new schedule)
What is story telling in Tableau?
In Tableau, Story is a sheet and user can embed multiple worksheets into it and can keep them in a sequence to present easily. In analytics world, this feature helps a lot especially to make connections in the data.
How many columns can be displayed in tableau report?
Maximum of 16 columns can be displayed in Tableau report.
How can you change the default number of columns in the report?
Analysis -> Table Layout -> Advanced -> Change number in rows/columns (maximum levels of row labels or maximum levels of horizontal row labels or maximum levels of column labels)
What will happen if you pull more than 16 into a report?
By default, Extra columns (>16) data will be concatenated and displayed as a single column.
The recommendation is not to use more number of columns in tableau as its visualization tool.
How can you schedule tableau data refresh?
Log into Tableau Server -> Click on Content - > Go to Data Sources -> Select Connection Name -> Select Refresh Schedule and assign appropriate schedule (In case if you do not have access to create new schedules, work with Tableau admin team to create new schedule)
Which are all the data operating systems can you install Tableau?
Tableau desktop can be installed on Windows 7 and anove, MacOS 10.10 and above
Tableau server can be installed only on windows. Linux version coming in the future.
Can Tableau server interact with any ftp server or shared location to refresh the data?
Yes. User should have access to read the file from ftp server.
Which are all the devices can Tableau support?
Desktop, Laptop, Mobile and Tablet.
What are Filters? How many types of filters are there in Tableau?
Filter is a condition, which restrict unwanted data and display only which is required based on condition.
In Tableau, Filters are 3 types.
o Quick filter
o Context filter
o Data source filter
What is the main difference between context filter to other filters?
Whenever user create context filter , Tableau will create a temporary tables for this particular filter set and other filters will be apply on the context filter data.
Example : When we create a context filter on region and we have chosen region as Americas.
Tableau will create a temporary table for this America data and other filters will be displayed on this region data only.
What is disadvantage of context 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 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.
What is the Difference between quick filter and Normal filter in tableau?
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.
How do you import your custom color pallets?
Sometimes, based on company standards we need to select particular set of colors. In such cases, it’s better to create our custom color pallets to make our job easier and save time.
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.
Example :
<?xml version='1.0'?>
<workbook>
<preferences>
<color-palette name="My Own Colors List" type="regular" >
<color>#00bceb</color>
<color>#005073</color>
</color-palette>
</preferences>
</workbook>
There are a number of file types and extensions in Tableau :
· Tableau Workbook (.twb).
· Tableau Packaged Workbook (.twbx).
· Tableau Datasource (.tds).
· Tableau Packaged Datasource (.tdsx).
· Tableau Data extract (.tde).
· Tableau Bookmark (.tdm).
· Tableau Map Source (.tms).
· Tableau Preferences (.tps)
If my dashboard is taking long time to render on server what could be the reason?
· Use Window_sum() instead of totals(). It is slow while extracting.
· Avoid quick filters in dashboards
· Source data bins give better performance than tableau bins.
· Use sql query instead of data blending if you are using RDBMS.
· Use less than 5 views in dashboard.
· Optimizing data extracts
When 8 worksheets are combined and made a complete dashboard if only 3 worksheets are modified due to some changes. Is it necessary to publish only changed worksheet or entire dashboard?
No need to publish entire workbook, Only changed worksheets should be good.
Have you come across any challenges faced when working with huge volumes of data?
o Report is running very slow.
o Data extraction is big problem and takes lot of time.
o If the data is huge and difficult to predict Alignment issues with data.
o Testing is a big task.
What is Union and can Tableau support Union for any data sources?
Union can combine the data from same data source.
Yes. Tableau supports Union. If the source is database, one can write custom SQL to union data.
If the source is excel then one can get an option to drag and drop data.
CSV FIles : Create data source connection for excel and then u should be able to see list of sheet names just below connection. Click on the New Union Just below sheets and drag & drop required sheets to New Union Pop up Window.
While scheduled refresh fails, what will happen to existing data in tableau?
When Tableau Online is unable to complete a scheduled refresh, an alert appears to indicate that the refresh has failed. If a scheduled refresh fails five consecutive times, Tableau Online suspends the refresh. When a refresh is suspended, Tableau Online does not try to run it again until you take an action that attempts to correct the cause of the failure.
General causes:
o Password might have expired
o Lost access
o Database was not reachable
o Incorrect file name (if source is file)
o Folder might not be available
o FTP server might be down
Which are all the browsers can Tableau support?
Below are recommended browsers for Tableau 10.0 and above.
Internet Explorer 11 , the Microsoft Edge browser, Chrome, Safari,
and Firefox browsers.
How can u improve performance of tableau server?
·
Avoid Quick filter
as much as possible. If required, we can use context filter for better
performance.
·
Use extracts instead
of live connection.
·
Use cache mechanism
·
Use incremental
extractions
·
Avoid the high
resolutions images
·
Adjust the count of application server and vizql server for hitting
cache.
·
Set both at 1x to 2x times the number of processing cores present on
the server
·
User should not access the dashboard while loading the data
What if customer is asking for data refreshed at minute level? What
would you suggest to the
customer?
It is performance
degrade. Using Java Script APIs we do that.
How can we create a report where we can switch views in dashboard?
Using parameters
What is Measure and Dimension in Tableau?
When you connect to Tableau data sources, Tableau categorize each
fields either as Dimension or Measure based on the data types assigned to it.
Strings ad Boolean
values will be assigned as Dimensions. When you click and drag a field from
the Dimensions area to Rows or Columns,
Tableau creates column or row headers.
Numbers and
quantitative columns will be assigned as Measures. When you drag a field from
the Measures area to Rows or Columns, Tableau creates a continuous axis.
How did you handle working
with huge volumes of data and how about performance tuning?
o Optimize the data model.
o Use statistics at database level
o Tune your indexes
o Partition the data in database level.