---
title: "Data Union"
slug: "data-union"
description: "Data Union in Dataddo: Easily add datasets from multiple sources to a single data flow. Learn how to match schemas, add sources, configure flows & troubleshoot."
updated: 2025-10-31T16:12:43Z
published: 2025-10-31T16:12:43Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dataddo.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Data Union

**Data union** combines datasets from multiple ***data sources*** in a single ***data flow***. It operates similarly to the `UNION` operator in SQL.

## Prerequisites

When creating your ***sources***, make sure they have **the exact same schemas**, including the same:

- **Number** of columns
- Column **names**/labels
- **Data types**

## How to Add More Sources to a Single Data Flow

1. Navigate to the **Flows** page and click on [**Create Flow**](https://app.dataddo.com/flow/new).
2. Click on **Connect Your Data** and select the first source.
3. Hover over the newly added source for the menu to show and click on **Combine**.
4. Select **Data Union** and add as many ***sources*** as needed (only compatible ones will be displayed).
5. Click on **Save Source** in the top right corner.
6. Add your ***data destination***, finish configuring your flow, and click on **Save Flow**.

![Data Flows - Click on Combine](https://cdn.document360.io/084ed225-3f99-4644-a2da-39ca0cd5ef45/Images/Documentation/Data%20Flows%20-%20Click%20on%20Combine.png)

![Data Flows - Celect Data Combination Method](https://cdn.document360.io/084ed225-3f99-4644-a2da-39ca0cd5ef45/Images/Documentation/Data%20Flows%20-%20Celect%20Data%20Combination%20Method.png)

## Troubleshooting

### Maximum Amount of Sources

In Dataddo, it is possible to union up to **100 *sources***. If you need to combine more ***sources***, it will be necessary to create multiple flows.

### Different Data Types

To check the data types of your source, click on the three dots, select **Edit** and navigate to the **Data Types** tab. If the data types don’t match (like in this example), you can change the data type of each column.

| Source 1 | Data type |
| --- | --- |
| Column A | **Float** |
| Column B | Integer |

| Source 2 | Data type |
| --- | --- |
| Column A | Integer --> change to **Float** |
| Column B | Integer |

![Change data type](https://cdn.document360.io/084ed225-3f99-4644-a2da-39ca0cd5ef45/Images/Documentation/Schema%20-%20Change%20data%20type.png)

A source is a collection of data from an authorized service that's been connected via a Dataddo connector. Data within the source is automatically refreshed based on the source's configuration.

Data flows allow you to orchestrate the integration of your data from various sources to your desired destinations. You may add multiple data sources with the same schema to one flow to merge data for a consolidated output.

A destination is the endpoint where the data from your sources will be loaded. Destinations include dashboarding tools, data warehouses, and other online services.