> ## Documentation Index
> Fetch the complete documentation index at: https://upstash-dx-3020.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# $sum

`$sum` computes the total of a field across matching documents.

If `missing` is set, missing fields contribute that fallback value.

By default, `$sum` returns `0` when no values are collected — either no documents match, or the matching documents all have a missing/null value for the field and no `missing` fallback is set. Set `nullIfNoMatch` to `true` to return `null` instead, so you can distinguish that case from a real total of zero.

### Compatibility

| Field Type  | Supported |
| ----------- | --------- |
| TEXT        | No        |
| U64/I64/F64 | Yes       |
| DATE        | Yes       |
| BOOL        | Yes       |
| KEYWORD     | No        |
| FACET       | No        |

Field must be `FAST`.

### Arguments

| Argument        | Type      | Required | Description                                                                  |
| --------------- | --------- | -------- | ---------------------------------------------------------------------------- |
| `field`         | `string`  | Yes      | Field to aggregate.                                                          |
| `missing`       | `number`  | No       | Fallback value for missing fields.                                           |
| `nullIfNoMatch` | `boolean` | No       | Return `null` instead of `0` when no values are collected. Default: `false`. |

<Tabs>
  <Tab title="TypeScript">
    ```ts theme={"system"}
    await index.aggregate({
      aggregations: {
        total_price: { $sum: { field: "price", nullIfNoMatch: true } },
      },
    });
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={"system"}
    index.aggregate(
        aggregations={
            "total_price": {
                "$sum": {"field": "price", "nullIfNoMatch": True}
            }
        },
    )
    ```
  </Tab>

  <Tab title="Redis CLI">
    ```bash theme={"system"}
    SEARCH.AGGREGATE products '{}' '{"total_price": {"$sum": {"field": "price", "nullIfNoMatch": true}}}'
    ```
  </Tab>
</Tabs>

### Output

```json theme={"system"}
{ "total_price": { "value": 360 } }
```

With `nullIfNoMatch: true`, an aggregation with no collected values (for example, the filter above matches no documents) returns:

```json theme={"system"}
{ "total_price": { "value": null } }
```

Without `nullIfNoMatch`, the same aggregation returns `0`. This option does not change results where at least one value was collected, including a real sum of zero.