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

# Allow records

export const entity_0 = "allow records processing rule"

The allow records [processing rule](/ingest/pipeline/processing-rules) preserves any
records that contain a key whose value matches a specified regular expression, and
then removes all other records.

## Configuration parameters

Use the parameters in this section to configure the {entity_0}. The
Telemetry Pipeline web interface uses the items in the **Name** column to
describe these parameters. [Pipeline configuration files](/ingest/pipeline/v2/configure/config-files)
use the items in the **Key** column as YAML keys.

| Name                    | Key           | Description                                                                                                                                                             | Default      |
| ----------------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------ |
| **Key**                 | `key`         | Required. The key whose value to validate against. If this key isn't present in a given record, that record is removed.                                                 | `log`        |
| **Regex**               | `regex`       | Required. The regular expression that determines which records to preserve. This expression is evaluated against the value of the specified key.                        | *none*       |
| **Match case** checkbox | `matchCase`   | Indicates whether the regular expression is case-sensitive.                                                                                                             | Not selected |
| **Regex engine**        | `regexEngine` | Required. The [engine](/ingest/pipeline/processing-rules#regex-engines) to parse your regular expression. Accepted values: `GNU`, `Oniguruma`, `PCRE2`, `POSIX`, `TRE`. | `PCRE2`      |
| **Comment**             | `comment`     | A custom note or description of the rule's function. This text is displayed next to the rule's name in the **Actions** list in the processing rules interface.          | *none*       |

## Example

Using the allow records rule lets you pare down telemetry data by retaining only
the records with key/value pairs that you explicitly choose to keep.

For example, given this sample log data:

```json theme={null}
{"timestamp":"2023-03-28T09:08:41.64283645Z","user_id":3,"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:42.643343109Z","user_id":4,"page_id":10,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:48.643600498Z","user_id":1,"page_id":50,"action":"click"}
{"timestamp":"2023-03-28T09:08:50.643773688Z","user_id":5,"page_id":40,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:51.643932272Z","user_id":1,"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:56.644080944Z","user_id":2,"page_id":40,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.64425954Z","user_id":3,"page_id":30,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.644317046Z","user_id":1,"page_id":20,"action":"view"}
{"timestamp":"2023-03-28T09:09:10.64447719Z","user_id":2,"page_id":50,"action":"purchase"}
{"timestamp":"2023-03-28T09:09:17.644810963Z","user_id":2,"page_id":10,"action":"view"}
{"timestamp":"2023-03-28T09:09:20.644994805Z","user_id":1,"page_id":50,"action":"view"}
```

A processing rule with the **Key** value `action` and the **Regex** value `purchase`
returns the following result:

```json theme={null}
{"user_id":3,"page_id":30,"action":"purchase","timestamp":"2023-03-28T09:08:41.64283645Z"}
{"user_id":4,"page_id":10,"action":"purchase","timestamp":"2023-03-28T09:08:42.643343109Z"}
{"user_id":5,"page_id":40,"action":"purchase","timestamp":"2023-03-28T09:08:50.643773688Z"}
{"user_id":1,"page_id":30,"action":"purchase","timestamp":"2023-03-28T09:08:51.643932272Z"}
{"user_id":2,"page_id":50,"action":"purchase","timestamp":"2023-03-28T09:09:10.64447719Z"}
```

This rule retained the records associated with user purchases and removed the records
associated with other actions, such as pageviews or clicks.

## Related rules

For a processing rule with the opposite effect, see
[block records](/ingest/pipeline/processing-rules/block-records).