> ## 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.

# pack_array

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

The `pack_array` function in APL creates an array from individual values or expressions. You can use this function to group related data into a single field, which can simplify handling and querying of data collections. It’s especially useful when working with nested data structures or aggregating data into arrays for further processing.

## 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">
    In Splunk SPL, you typically use functions like `mvappend` to create multi-value fields. In APL, the `pack_array` function serves a similar purpose by combining values into an array.

    <CodeGroup>
      ```sql Splunk example theme={null}
      | eval array_field = mvappend(value1, value2, value3)
      ```

      ```kusto APL equivalent theme={null}
      | extend array_field = pack_array(value1, value2, value3)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    In ANSI SQL, arrays are often constructed using functions like `ARRAY`. The `pack_array` function in APL performs a similar operation, creating an array from specified values.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT ARRAY[value1, value2, value3] AS array_field;
      ```

      ```kusto APL equivalent theme={null}
      | extend array_field = pack_array(value1, value2, value3)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

```kusto theme={null}
pack_array(value1, value2, ..., valueN)
```

### Parameters

| Parameter | Description                                |
| --------- | ------------------------------------------ |
| `value1`  | The first value to include in the array.   |
| `value2`  | The second value to include in the array.  |
| `...`     | Additional values to include in the array. |
| `valueN`  | The last value to include in the array.    |

<Note>
  The wildcard `*` in `pack_array(*)` is useful to pack all values from the current row into an array, but it increases query complexity and decreases stability and performance.

  `pack_array(*)` packs only the values, not the field names. For key-value pairs, use `bag_pack(*)` instead.
</Note>

### Returns

An array containing the specified values in the order they are provided.

## Use case example

Use `pack_array` to consolidate span data into an array for a trace summary.

**Query**

```kusto theme={null}
['otel-demo-traces']
| extend span_summary = pack_array(['service.name'], kind, duration)
```

[Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'otel-demo-traces'%5D%20%7C%20extend%20span_summary%20%3D%20pack_array\(%5B'service.name'%5D%2C%20kind%2C%20duration\)%22%7D)

**Output**

| service.name | kind   | duration | span\_summary                    |
| ------------ | ------ | -------- | -------------------------------- |
| frontend     | server | 123ms    | \["frontend", "server", "123ms"] |

This query creates a concise representation of span details.

## List of related functions

* [array\_slice](/apl/scalar-functions/array-functions/array-slice): Extracts a subset of elements from an array.
* [array\_concat](/apl/scalar-functions/array-functions/array-concat): Combines multiple arrays.
* [array\_length](/apl/scalar-functions/array-functions/array-length): Returns the number of elements in an array.