> For the complete documentation index, see [llms.txt](https://resources.less.tech/less-tech/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://resources.less.tech/less-tech/modelling/action-guides/merge/append.md).

# Append

Combine data sets by appending observations together. Helpful for transferring important columns from one data set to another.

{% hint style="warning" %}
Be mindful of the Append. The number of rows in your data set can easily grow exponentially when using the Append Action. The number of rows after the Append Action equals the multiplication of rows from the two data sets you send into the Append Action. So if you have two datasets with 100 rows that you want to append, you will end up with 10.000 rows (100\*100=10.000).
{% endhint %}

{% embed url="<https://www.loom.com/share/7299501783904b0e8ccf7d8af7747e70>" %}


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