---
title: Join processor
description: The Join processor concatenates the values of multiple fields into a single field with a delimiter between them. To join fields: Select Create → Create...
url: https://www.elastic.co/elastic/docs-builder/docs/3016/solutions/observability/streams/management/extract/join
products:
  - Elastic Cloud Enterprise
  - Elastic Cloud Hosted
  - Elastic Cloud Serverless
  - Elastic Cloud on Kubernetes
  - Elastic Observability
  - Elastic Stack
  - Elasticsearch
  - Kibana
applies_to:
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Planned
---

# Join processor
The **Join** processor concatenates the values of multiple fields into a single field with a delimiter between them.
To join fields:
1. Select **Create** → **Create processor**.
2. Select **Join** from the **Processor** menu.
3. Set the **Source Fields** to the fields you want to join.
4. Set the **Delimiter** to the separator placed between values.
5. Set the **Target field** where the joined result is stored.


## YAML reference

In [YAML mode](/elastic/docs-builder/docs/3016/solutions/observability/streams/management/extract#streams-editing-yaml-mode), configure the join processor using the following parameters. For the complete Streamlang syntax, refer to the [Streamlang reference](https://www.elastic.co/elastic/docs-builder/docs/3016/solutions/observability/streams/management/streamlang).

| Parameter        | Type     | Required | Description                                                      |
|------------------|----------|----------|------------------------------------------------------------------|
| `from`           | string[] | Yes      | Source fields to join.                                           |
| `delimiter`      | string   | Yes      | Delimiter placed between values.                                 |
| `to`             | string   | Yes      | Target field.                                                    |
| `ignore_missing` | boolean  | No       | When `true`, skip this processor if any source field is missing. |

```yaml
- action: join
  from:
    - attributes.last_name
    - attributes.first_name
  delimiter: ","
  to: attributes.full_name
```