# Saved data sources and multiple connections

*Tableau Desktop Foundations Study Guide · Connecting to and Preparing Data · Last updated October 29, 2026 · https://www.certifyforce.com/study-guide/tableau-desktop-foundations/connecting-to-and-preparing-data/saved-data-sources-and-multiple-connections*

What a saved .tds stores (connection information plus calculations, groups, sets, bins and default field properties) versus a packaged .tdsx, how to reuse it from the Connect pane, and how a second connection in one data source enables a cross-database join.

- Certification: Salesforce Tableau Desktop Foundations
- Exam section: Connecting to and Preparing Data
- Study guide: https://www.certifyforce.com/study-guide/tableau-desktop-foundations

**Official exam objective:**

> Create live connections and extracts: Create a live connection to a data source; Explain the differences between using live connections versus extracts; Create an extract; Save metadata properties in a .TDS; Create a data source that uses multiple connections.

## What the exam expects

- Save a data source with Add to Saved Data Sources and list what a .tds file stores.
- Choose between a .tds and a packaged .tdsx based on whether everyone can reach the underlying data.
- Reconnect to a saved data source from the Saved Data Sources section of the Connect pane or with File > Open.
- Build a data source with more than one connection and join tables across them, and name the data that can't take part.
- Key terms: **.tds** (data source file: connection information and metadata, no data); **.tdsx** (packaged data source: the .tds plus a copy of local file data or extracts); **metadata** (calculated fields, groups, sets, bins, renamed fields and default properties layered on the data); **multi-connection data source** (one data source holding connections to more than one database or file); **cross-database join** (a join between tables from different connections).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| .tds contents | Data source type, connection information, groups, sets, calcs, bins, default field properties | [Save Data Sources](https://help.tableau.com/current/pro/desktop/en-us/export_connection.htm) |
| .tds holds data? | No; only what is needed to connect plus metadata | [Save Data Sources](https://help.tableau.com/current/pro/desktop/en-us/export_connection.htm) |
| .tdsx adds | A copy of local file-based data or extracts, in one zipped file | [Save Data Sources](https://help.tableau.com/current/pro/desktop/en-us/export_connection.htm) |
| Save command | Right-click the data source in the Data pane > Add to Saved Data Sources | [Save Data Sources](https://help.tableau.com/current/pro/desktop/en-us/export_connection.htm) |
| Default save folder | Datasources folder of the Tableau repository | [Save Data Sources](https://help.tableau.com/current/pro/desktop/en-us/export_connection.htm) |
| Reconnect | Saved data sources section of the Connect pane, or File > Open | [Connect to Your Data](https://help.tableau.com/current/pro/desktop/en-us/basicconnectoverview.htm) |
| Add a connection | Add next to Connections in the Data Source page left pane | [Join Your Data](https://help.tableau.com/current/pro/desktop/en-us/joining_tables.htm) |
| Multi-connection on a sheet | Functions as one combined data source | [Join Your Data](https://help.tableau.com/current/pro/desktop/en-us/joining_tables.htm) |
| Connection colors | Tables in the canvas and columns in the grid are colored by connection | [Join Your Data](https://help.tableau.com/current/pro/desktop/en-us/joining_tables.htm) |
| Can't cross-database join | Cube data, most extract-only data, published Tableau data sources | [Join Your Data](https://help.tableau.com/current/pro/desktop/en-us/joining_tables.htm) |

## Check yourself

- Why does a .tds still need the original file or database to show any data?
- When does Tableau prompt you to locate or replace data after opening a .tds?
- Why do rows with null join keys drop out of a join after you add a second connection?
- Why can't you union a table from one connection with a table from another?
- What does a missing connector in the Add list tell you?

## Sources

- [Save Data Sources](https://help.tableau.com/current/pro/desktop/en-us/export_connection.htm)
- [Join Your Data](https://help.tableau.com/current/pro/desktop/en-us/joining_tables.htm)
- [Connect to Your Data](https://help.tableau.com/current/pro/desktop/en-us/basicconnectoverview.htm)
- [Navigate Data Sources in the Data Pane](https://help.tableau.com/current/pro/desktop/en-us/multipleconnections_navigateconnections.htm)
- [Plan the Data Source](https://help.tableau.com/current/pro/desktop/en-us/datasource_plan.htm)
- [Data Source Page](https://help.tableau.com/current/pro/desktop/en-us/environment_datasource_page.htm)
- [Union Your Data](https://help.tableau.com/current/pro/desktop/en-us/union.htm)
- [Packaged Workbooks](https://help.tableau.com/current/pro/desktop/en-us/save_savework_packagedworkbooks.htm)
- [Extract Your Data](https://help.tableau.com/current/pro/desktop/en-us/extracting_data.htm)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 7 linked practice questions, and unlimited timed mock exams are included with the Tableau Desktop Foundations pack (USD $19): https://www.certifyforce.com/practice-exams