# array_agg function
Aggregate values (including nulls) as an array.
The `array_agg(value)` function aggregates values (including nulls) as an array.
The input values to the aggregate can be [filtered](../filters).

## Syntax



```mzsql
array_agg ( <value>
  [ORDER BY <col_ref> [ASC | DESC] [NULLS FIRST | NULLS LAST] [, ...]]
)
[FILTER (WHERE <filter_clause>)]

```

| Syntax element | Description |
| --- | --- |
| `<value>` | The values you want aggregated.  |
| **ORDER BY** `<col_ref>` [**ASC** \| **DESC**] [**NULLS FIRST** \| **NULLS LAST**] [, ...] | Optional. Specifies the ordering of values within the aggregation. If not specified, incoming rows are not guaranteed any order.  |
| **FILTER** (WHERE `<filter_clause>`) | Optional. Specifies which rows are sent to the aggregate function. Rows for which the `<filter_clause>` evaluates to true contribute to the aggregation. See [Aggregate function filters](/sql/functions/filters) for details.  |


## Signatures

Parameter | Type | Description
----------|------|------------
_value_ | [any](../../types) | The values you want aggregated.

### Return value

`array_agg` returns the aggregated values as an [array](../../types/array/).

This function always executes on the data from `value` as if it were sorted in ascending order before the function call. Any specified ordering is
ignored. If you need to perform aggregation in a specific order, you must specify `ORDER BY` within the aggregate function call itself. Otherwise incoming rows are not guaranteed any order.

## Details

### Usage in dataflows

While `array_agg` is available in Materialize, materializing `array_agg(values)`
is considered an incremental view maintenance anti-pattern. Any change to the data
underlying the function call will require the function to be recomputed entirely,
discarding the benefits of maintaining incremental updates.

Instead, we recommend that you materialize all components required for the
`array_agg` function call and create a non-materialized view using `array_agg`
on top of that. That pattern is illustrated in the following statements:

```mzsql
CREATE MATERIALIZED VIEW foo_view AS SELECT * FROM foo;
CREATE VIEW bar AS SELECT array_agg(foo_view.bar) FROM foo_view;
```

## Examples

```mzsql
SELECT
    title,
    ARRAY_AGG (
        first_name || ' ' || last_name
        ORDER BY
            last_name
    ) actors
FROM
    film
GROUP BY
    title;
```