# Pipeline

The Pipeline feature helps you track all the changes that you have made on all your databases in a project. You can go to any project in your workspaces and find the **`Pipeline`** button at the top-right corner of the page.

<figure><img src="/files/HGhJj7aovKxs1OoF4MtG" alt=""><figcaption></figcaption></figure>

Then, you can see a tree diagram that shows all the history of data editing and the relationships between tables within the project. Each action is presented as a small icon and you can click the icon to display the table at that time. If you want to edit, add or delete actions in the tree diagram, you can use [Pipeline Editor](/acho-studio/data-prep-projects/pipeline-editor.md). The relationship is especially obvious when you use the [Join](/acho-studio/data-prep-projects/applying-actions/combine-tables/join.md) or [Union](/acho-studio/data-prep-projects/applying-actions/combine-tables/union.md) actions to merge multiple tables.&#x20;

<figure><img src="/files/xEQNazX98G73ZRiUkfaC" alt=""><figcaption><p>Pipeline is composed of a sequence of actions </p></figcaption></figure>

However, the tree diagram currently cannot show the lines connecting tables in the following situations:

1. When you use [SQL Editor](/acho-studio/data-prep-projects/applying-actions/tools/sql-editor.md) to join or union multiple tables
2. When you add a JOIN or Union action through [Pipeline Editor](/acho-studio/data-prep-projects/pipeline-editor.md)


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