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

# Using Composite Key in NCE

Use this option to create new NCE records when a new primary key and composite key(s) combination is ingested and update the existing records, if the same combination is ingested again.

### When Composite Key Is Enabled

When the **Composite Key** is enabled, Zeotap CDP retains both existing and incoming records in the user profile. This approach is useful when merging customer data and non-customer data using multiple Join Keys. Each time a unique combination of the primary key and composite key(s) is ingested, a new NCE record is created. If the same combination is ingested again, the existing record is updated.

**Example**

A customer (UCID: 12345) has multiple registered phone numbers. The append operation ensures all numbers are retained in the profile instead of replacing existing ones.

| **UCID** | **Phone Number** |
| :------- | :--------------- |
| 12345    | 555-1234         |
| 12345    | 555-5678         |

### When Composite Key Is Disabled

When the **Composite Key** is disabled, Zeotap CDP updates existing records or adds new records based on the Join Key. This approach maintains data consistency and prevents duplication.

**Example**

A customer (UCID: 67890) has multiple subscription plans (family, work, personal). The upsert operation works as follows:

* **Existing records are updated**: If the customer already has a **work plan**, the system updates it with the latest details.
* **New records are added**: If the customer adds a **family plan**, it is added under the same UCID without overwriting other plans.

| **UCID** | **Subscription Plan** | **Status** |
| :------- | :-------------------- | :--------- |
| 67890    | Work Plan             | Updated    |
| 67890    | Family Plan           | Added      |

By selecting the appropriate operation, you can control how data is managed in the user profile.

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