Blending data sources in Tableau - Step-by-Step Guide

Introduction

Blending data sources in Tableau lets you combine data from different places without merging them into one file. This helps when you want to compare or analyze data that lives separately, like sales numbers and customer info from different systems.

When your sales data is in one database and customer feedback is in another, and you want to see them together.

When you have monthly sales in Excel and yearly targets in a cloud database and want to compare them.

When you want to create a dashboard that shows product inventory from one system and shipping data from another.

When you need to analyze marketing campaign results stored in one source with website traffic data in another.

When you want to avoid copying or merging large datasets but still want combined insights.

Steps

Step 1: Connect to your primary data source

- Data pane

Primary data source appears in the Data pane with its fields listed

Step 2: Connect to your secondary data source

- Data pane

Secondary data source appears below the primary source in the Data pane

Step 3: Drag a field from the primary data source to Rows or Columns shelf

- Worksheet view

Tableau creates a view using the primary data source

Step 4: Drag a related field from the secondary data source to the view

- Data pane

A link icon appears next to the secondary data source, indicating blending is active; data from both sources combine in the view

Step 5: Click the link icon next to the secondary data source

- Data pane

Blending fields are shown; you can add or remove linking fields to control how data blends

Step 6: Adjust the linking fields if needed

- Data pane blending options

The view updates to reflect the new blend relationship

Before vs After

Before

Only data from the primary source is visible in the worksheet, showing sales by region

After

Sales by region from the primary source combined with customer satisfaction scores from the secondary source appear in the worksheet

Settings Reference

Linking Fields

📍 Data pane next to secondary data source

Defines which fields Tableau uses to match data between sources

Default: Automatically linked by common field names

Primary vs Secondary Data Source

📍 Data pane order and icon

Determines which data source drives the view and which blends in

Default: First connected data source is primary

Common Mistakes

Not linking fields correctly between data sources

Tableau cannot match data rows properly, so the blended data shows incorrect or missing values

Ensure the linking fields have the same data type and matching values in both sources

Using blending when a join would be better

Blending is slower and less flexible for detailed row-level combinations

Use data joins in Tableau Prep or the data source if you need detailed combined rows

Summary

Blending data sources lets you combine data from different places without merging files.

You set one data source as primary and link fields to a secondary source to blend data.

Make sure linking fields match well to get accurate combined results.