Data in Tableau

1. Connecting to Data

1) Live connection(default)

• more beneficial than using an extract
  • Analyzing and tracking real time flight updates
  • Analyzing real time data from production systems
  • Analyzing real time stock prices
• Through Web Data Connectors, Tableau can interact with web data in real-time
• Live connections are not typically used to improve dashboard performance
  cf. Data extracts, Aggregated extracts, Filters, Calculated fields

2) Extract connection(a subset of original data source)

Tableau Data Extract (.tde) is a snapshot of the data the Tableau stores locally.

• supports large data set
• help improve performance
• support additional functionality
• provide offline access to your data
• When connections to a database are very slow

refreshing the data

• a full refresh, which replaces all of the contents in the extract
• an incremental refresh, which only adds rows that are new since the previous refresh

Options available when creating extract

• Extract Data - Edit
  • Data Storage(logical/physical table)
  • Filters
  • Aggregation
  • Number of Rows
  • History
  • Hide All Unused Fields

Don't connect directly to the extract

• The table names will be different
• You cannot refresh the extract
• The data model and relationships will be lost

how to edit the data source

• Data Menu - Select a Data Source - Edit Data Source

Edit Data Sources

• Replace References

to display the complete list of potential data connections when you connect to a server

• To a Server → More

how to add additional connections to different databases

• From the Connections pane, select Add

2. Tableau File Types and Folders

Data Source (.tds)

• only the information needed to connect to the data source
  • Data Source Type
  • Connection information specified on the data source page
  • Groups, sets, calculated fields, bins
  • Default field properties; for example, number formats, aggregation, and sort order
• do not save any visualizations

Packaged Data Source (.tdsx)

• data source + original data
• do not save any visualizations

Workbooks (.twb)

• worksheets, dashboards, stories

Packaged Workbooks (.twbx)

• data source, original data, visualizations

3. Creating Joins

• 4 joins are available in Tableau
• You can join a maximum of 32 Tables in Tableau
• Right-click a logical table and click on open to go to the Join/Union canvas in the physical layer and add joins or unions.
• Double-click a logical table to go to the Join/Union canvas in the physical layer and add joins or unions.
• You can join tables in Tableau using custom SQL queries.
• using a specific join type
• when you need to use row-level security
• when you need to use a data model that supports shared dimensions

4. Relationships in Tableau

• logical layer(relationship)
  each logical layer has at least 1 physical layer
• physical layer(join, union)
• when the data sets include similar data aggregated at different levels of detail

• Questions about Relationships

• How Relationships Differ from Joins

• Multi-table Data Analysis

5. Creating Unions

• by appending values (rows) from one table to another
• Tables cannot be union from different databases
• The union columns need to have the same data type

6. Creating Blends

• to change how the data source is configured on a sheet-by-sheet basis
• using a left join
  A join combines the data and then aggregates
  A blend aggregates and then combines the data
• combining data from multiple sources
  primary data source(blue color), secondary data source(orange color)
  with "linking field"
• not having a blended data source
• An asterisk(*) in a view with blended data indicates multiple values

7. Renaming Fields

태블로에서 필드명을 변경하면 원래 데이터의 이름은 변경되지 않는다.
1) Preview → Double click the field
2) Metadata properties → Rename Field Name
3) 데이터 패널에서 Rename

• use the field's drop-down menu and select Rename
• click and hold on the field until the name is editable

8. Creating Aliases

• ONLY for dimensions
• Measures, Dates, and Continuous dimension (X)

9. Manage Metadata

• To view all hidden fields
• To see the filed name in the original data source
• To see the table a field belongs to

10. Data interpreter

• To clean and automatically fix the data issues in our data source
  (Excel, CSV, PDF, and Google Sheets)

looking at underlying data in your workbook

• Use the View Data option in the Data Pane
• Use the View Data option by right clicking a mark
• Use the View Data option in the Analysis Toolbar Menu