> ## 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.

# max_of

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

Use the `max_of` function in APL (Axiom Processing Language) to return the maximum value from a list of scalar expressions. You can use it when you need to compute the maximum of a fixed set of values within each row, rather than across rows like with [aggregation functions](/apl/aggregation-function/statistical-functions). It’s especially useful when the values you want to compare come from different columns or are dynamically calculated within the same row.

Use `max_of` when you want to:

* Compare multiple fields in a single event to determine the highest value.
* Perform element-wise maximum calculations in datasets where values are spread across columns.
* Evaluate conditional values and select the highest one on a per-row basis.
* Ensure a minimum value. For example, `max_of(value, 0)` always returns greater than 0.

## 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 doesn’t provide a direct function equivalent to `max_of`. However, you can use the `eval` command with nested `if` statements or custom logic to emulate similar functionality on a per-event basis.

    <CodeGroup>
      ```sql Splunk example theme={null}
      eval max_value=if(a > b and a > c, a, if(b > c, b, c))
      ```

      ```kusto APL equivalent theme={null}
      extend max_value = max_of(a, b, c)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    ANSI SQL doesn’t offer a built-in function like `max_of` to compute the maximum across expressions in a single row. Instead, you typically use `GREATEST`, which serves a similar purpose.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT GREATEST(a, b, c) AS max_value FROM table
      ```

      ```kusto APL equivalent theme={null}
      extend max_value = max_of(a, b, c)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

```kusto theme={null}
max_of(Expr1, Expr2, ..., ExprN)
```

### Parameters

The function takes a comma-separated list of expressions to compare. All values must be of the same type.

### Returns

The function returns the maximum value among the input expressions. The type of the result matches the type of the input expressions. All expressions must be of the same or compatible types.

## Use case example

You have two data points for the size of HTTP responses: header size and body size. You want to find the maximum of these two values for each event.

**Query**

```kusto theme={null}
['sample-http-logs']
| extend max_size = max_of(resp_header_size_bytes, resp_body_size_bytes)
| project _time, id, resp_header_size_bytes, resp_body_size_bytes, max_size
```

[Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'sample-http-logs'%5D%20%7C%20extend%20max_size%20%3D%20max_of\(resp_header_size_bytes%2C%20resp_body_size_bytes\)%20%7C%20project%20_time%2C%20id%2C%20resp_header_size_bytes%2C%20resp_body_size_bytes%2C%20max_size%22%7D)

**Output**

| \_time           | id                                   | resp\_header\_size\_bytes | resp\_body\_size\_bytes | max\_size |
| ---------------- | ------------------------------------ | ------------------------- | ----------------------- | --------- |
| May 15, 11:18:53 | 4baad81e-2bca-408f-8a47-092065274037 | 39 B                      | 2,805 B                 | 2,805     |
| May 15, 11:18:53 | 05b257c0-8f9d-4b23-8901-c5f288abc30b | 24 B                      | 988 B                   | 988       |
| May 15, 11:18:53 | b34d937c-527a-4a05-b88f-5f3dba645de6 | 72 B                      | 4,399 B                 | 4,399     |
| May 15, 11:18:53 | 12a623ec-8b0d-4149-a9eb-d3e18ad5b1cd | 34 B                      | 1,608 B                 | 1,608     |
| May 15, 11:18:53 | d24f22a7-8748-4d3d-a815-ed93081fd5d1 | 84 B                      | 4,080 B                 | 4,080     |
| May 15, 11:18:53 | 3cc68be1-bb9a-4199-bf75-62eef59e3a09 | 76 B                      | 5,117 B                 | 5,117     |
| May 15, 11:18:53 | abadabac-a6c0-4ff2-80a1-11143d7c408b | 41 B                      | 2,845 B                 | 2,845     |