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

<AgentInstructions>

## Submitting Feedback

If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:

POST https://axiom.co/docs/feedback

```json
{
  "path": "/apl/scalar-functions/hash-functions/hash-md5",
  "feedback": "Description of the issue"
}
```

Only submit feedback when you have something specific and actionable to report.

</AgentInstructions>

# hash_md5

> This page explains how to use the hash_md5 function in APL.

## Introduction

The `hash_md5` function returns the MD5 hash of a scalar value as a 32-character hexadecimal string. Use it to anonymize personally identifiable information while preserving joinability, detect duplicate records across datasets, or generate consistent bucket keys for grouping.

MD5 produces a 128-bit digest that's fast to compute. It isn't suitable for cryptographic security, but is appropriate for data deduplication, checksumming, and non-security anonymization tasks. For security-sensitive use cases, use [`hash_sha256`](/apl/scalar-functions/hash-functions/hash-sha256) or [`hash_sha512`](/apl/scalar-functions/hash-functions/hash-sha512) instead.

## For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

<AccordionGroup>
  <Accordion title="Splunk SPL users">
    Splunk provides the `md5(X)` function that returns a 32-character hex string. APL's `hash_md5` works the same way.

    <CodeGroup>
      ```sql Splunk example theme={null}
      ... | eval hashed_id = md5(id)
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend hashed_id = hash_md5(id)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    ANSI SQL has no standard MD5 function, but most databases provide one: MySQL's `MD5()`, PostgreSQL's `md5()`. APL's `hash_md5` returns the same 32-character lowercase hex digest.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT MD5(id) AS hashed_id FROM sample_http_logs
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend hashed_id = hash_md5(id)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

```kusto theme={null}
hash_md5(source)
```

### Parameters

| Name   | Type   | Required | Description                                                    |
| ------ | ------ | -------- | -------------------------------------------------------------- |
| source | scalar | Yes      | The value to hash. APL converts it to a string before hashing. |

### Returns

The MD5 hash of `source` as a 32-character lowercase hexadecimal string.

## Use case examples

<Tabs>
  <Tab title="Log analysis">
    Anonymize user IDs before counting requests per user to protect PII in shared dashboards.

    **Query**

    ```kusto theme={null}
    ['sample-http-logs']
    | extend hashed_id = hash_md5(id)
    | summarize request_count = count() by hashed_id
    | top 5 by request_count
    ```

    [Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B%27sample-http-logs%27%5D%20%7C%20extend%20hashed_id%20%3D%20hash_md5%28id%29%20%7C%20summarize%20request_count%20%3D%20count%28%29%20by%20hashed_id%20%7C%20top%205%20by%20request_count%22%7D)

    **Output**

    | hashed\_id                       | request\_count |
    | -------------------------------- | -------------- |
    | b980a9c041dbd33d5893fad65d33284b | 128            |
    | 3f7a2c1e8d4b6f9e0c5d3a7b2e4f8c1d | 97             |
    | 9c2e4a6f1d3b7e8c5a2f4d6b9e1c3a7f | 85             |
    | 1a3c5e7b9f2d4a6c8e0b3f5d7a9c1e3b | 74             |
    | 7f9e1c3a5b2d4f6e8c0a3b5d7e9f1c3a | 69             |

    The query replaces raw user IDs with MD5 hashes before aggregating, so the busiest users are visible without exposing their original identifiers.
  </Tab>

  <Tab title="OpenTelemetry traces">
    Hash trace IDs to create stable, anonymized surrogate keys for grouping.

    **Query**

    ```kusto theme={null}
    ['otel-demo-traces']
    | extend hashed_trace = hash_md5(trace_id)
    | project _time, ['service.name'], hashed_trace, duration
    | take 10
    ```

    [Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B%27otel-demo-traces%27%5D%20%7C%20extend%20hashed_trace%20%3D%20hash_md5%28trace_id%29%20%7C%20project%20_time%2C%20%5B%27service.name%27%5D%2C%20hashed_trace%2C%20duration%20%7C%20take%2010%22%7D)

    **Output**

    | \_time              | service.name | hashed\_trace                    | duration |
    | ------------------- | ------------ | -------------------------------- | -------- |
    | 2024-01-15 10:23:01 | frontend     | a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 | 320ms    |
    | 2024-01-15 10:23:02 | checkout     | f6e5d4c3b2a1f6e5d4c3b2a1f6e5d4c3 | 875ms    |
    | 2024-01-15 10:23:03 | cart         | 2c4e6a8b0d2c4e6a8b0d2c4e6a8b0d2c | 140ms    |

    The query projects the hashed trace ID alongside service name and duration so you can analyze traces without exposing the original trace identifiers.
  </Tab>
</Tabs>

## List of related functions

* [hash\_sha1](/apl/scalar-functions/hash-functions/hash-sha1): Returns a 40-character SHA-1 hex digest. Use `hash_sha1` when you need a larger digest than MD5 but legacy compatibility matters.
* [hash\_sha256](/apl/scalar-functions/hash-functions/hash-sha256): Returns a 64-character SHA-256 hex digest. Use `hash_sha256` for security-sensitive hashing.
* [hash\_sha512](/apl/scalar-functions/hash-functions/hash-sha512): Returns a 128-character SHA-512 hex digest for maximum hash strength.
* [hash](/apl/scalar-functions/hash-functions/hash): Returns a signed 64-bit integer hash. Use `hash` when you need a compact numeric key rather than a hex string.