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

# Rollup

> Aggregate a value across every related record.

## Overview

A Rollup reaches through a [Relation](/data/properties/select/relation) and
summarises what it finds on the other side: total contract value across a
company's deals, the newest activity date on a contact, how many open tickets an
account has. Pick it from **Complex** in the property type list.

It has no stored value. It's recomputed on read, so it's always current and
**read-only**.

## Configuration

| Setting           | What it does                                                                                                                  |
| ----------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| Relation property | Which relation to follow to reach the related records.                                                                        |
| Target property   | The property on the related records to aggregate.                                                                             |
| Calculation       | How to combine them: sum, count, average, min, max, and so on. `Show original` passes the values through without aggregating. |

## What it stores

Nothing. The value is calculated each time the record is read, from whatever
the related records currently hold.

## Examples

* **Total pipeline** on a Company, sum the Amount of every related Deal.
* **Open tickets** on an Account, count related Tickets.
* **Last touched** on a Contact, max of the related Activities' dates.

<Note>
  Because a rollup is computed, it can't be written over the API and can't be
  set by an automation, sending a value for one is ignored. Change the related
  records and the rollup follows.
</Note>

## See also

* [Formula](/data/properties/complex/formula): compute from fields on the *same* record.
* [Relation](/data/properties/select/relation): the link a rollup travels.


## Related topics

- [Usage](/data/properties/complex/usage.md)
- [Overview](/data/properties/complex/overview.md)
- [Grade](/data/properties/complex/grade.md)
- [Coaching Trends](/comms/coaching/trends.md)
- [How the schema works](/dev/api-reference/schema.md)