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

# Append

> Combine two datasets that share common columns into a single dataset by stacking them.

## Description

This step combines two datasets which share common columns into a single dataset by stacking them upon each other.

***

## Application

Often in engineering, data is not always in one big table but distributed over several tables. That is, you start with different tables that you might want to append together to obtain one big table that you can use for cleaning, visualisation, comparison, etc.

***

## How to use

* Select the **Datasets** that should be combined into a single dataset.
* Enable **Add dataset name column** if you want to identify the source dataset in the new combined dataset.
* Enable **Save output under different name** if you want to save the resulting dataset under a new name. If this option is disabled the new combined dataset will be saved under the name of the first dataset in the list.
* Click **Apply** to run the append operation.

***

## Examples

### Both datasets share all columns

Consider the two datasets which have two common columns each:

| **A** | **B** |
| ----- | ----- |
| 1     | 3     |
| 2     | 4     |

| **A** | **B** |
| ----- | ----- |
| 5     | 7     |
| 6     | 8     |

The resulting dataset after running Append would look like this:

| **A** | **B** |
| ----- | ----- |
| 1     | 3     |
| 2     | 4     |
| 5     | 7     |
| 6     | 8     |

If the option **Add dataset name column** was enabled the resulting dataset would look like this:

| **A** | **B** | **Dataset Name** |
| ----- | ----- | ---------------- |
| 1     | 3     | Dataset 1        |
| 2     | 4     | Dataset 1        |
| 5     | 7     | Dataset 2        |
| 6     | 8     | Dataset 2        |

Not all columns are shared in common

Consider the two datasets which have two common columns each:

| **A** | **B** | **C** |
| ----- | ----- | ----- |
| 1     | 3     | 5     |
| 2     | 4     | 6     |

Dataset 1

| **A** | **B** | **C** |
| ----- | ----- | ----- |
| 10    | 12    | 14    |
| 11    | 13    | 15    |

Dataset 2

The resulting dataset after running append would be this:

| A  | B  | C | D  |
| -- | -- | - | -- |
| 1  | 3  | 5 | -  |
| 2  | 4  | 6 | -  |
| 10 | 12 | - | 14 |
| 11 | 13 | - | 15 |

No data is lost by the append operation. All columns will be added to the final dataset but columns which are not shared by all involved datasets are going to produce empty cells (i.e. missing data).