> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/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`. |

> [tab] TypeScript
>
> ```ts theme={"system"}
> await index.aggregate({
>   aggregations: {
>     total_price: { $sum: { field: "price", nullIfNoMatch: true } },
>   },
> });
> ```

> [tab] Python
>
> ```python theme={"system"}
> index.aggregate(
>     aggregations={
>         "total_price": {
>             "$sum": {"field": "price", "nullIfNoMatch": True}
>         }
>     },
> )
> ```

> [tab] Redis CLI
>
> ```bash theme={"system"}
> SEARCH.AGGREGATE products '{}' '{"total_price": {"$sum": {"field": "price", "nullIfNoMatch": true}}}'
> ```

### 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.


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