> For the complete documentation index, see [llms.txt](https://help.adalo.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.adalo.com/database/relationships/many-to-many.md).

# Many-to-Many

{% hint style="warning" %}
Having too many relationship properties ***(especially many-to-many)*** on a single collection definitely degrades performance in Adalo, especially at scale.
{% endhint %}

## Learn About Many-to-Many Relationships

{% embed url="<https://youtu.be/M1o0RBUrBSI>" %}

***

#### **Many-to-Many Relationship**

A many-to-many relationship exists when records in one collection can be connected to multiple records in another collection, and vice versa.

#### **Example: Tasks and Users**

* One task can be assigned to multiple users **AND** One user can be assigned to multiple tasks

{% hint style="danger" %}

* **M-M Relationships can not be added on creation of new record in database.**
* **M-M Relationships can not be set upon Create Action for new record.**
  {% endhint %}

***

## **Relationships vs Join Collections**

Relationships are essential for organizing data in Adalo, but they come with performance trade-offs. Understanding the difference between direct relationships and junction collections allows you to make informed decisions about your data structure.

* **Use relationships** for simple, one-to-many connections and small datasets
* **Use junction collections** when possible for many-to-many relationships and before number of relationships to any single collection becomes an issue
* **Plan ahead:** Choose your data structure with growth in mind


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