# Cutoff Date

Some [activity selectors](https://getstream.io/activity-feeds/docs/dotnet-csharp/activity-selectors/) have no cutoff by default and scan your feed's entire history on every read. That's fine in development, but with a filter on a large production dataset it becomes a performance risk.

Without a filter, the newest activities are usually enough and the read is fast. Add a filter with no cutoff and the search has no time bound: a selective filter (few or no recent matches) can scan huge amounts of history and time out with a 500, often only after launch once data has grown. A `cutoff_window` bounds the scan, so a selective filter returns "nothing in the window" quickly.

**Rule of thumb:** if a selector uses a filter that runs at read time, set a `cutoff_window`.

## Which selectors need this

| Selector            | Default cutoff   | Set a cutoff when filtering?       |
| ------------------- | ---------------- | ---------------------------------- |
| `following`         | none (unbounded) | No (only fast tag filters allowed) |
| `current_feed`      | none (unbounded) | Yes, with richer filters           |
| `proximity`         | none (unbounded) | Yes                                |
| `follow_suggestion` | none (unbounded) | Yes                                |
| `query`             | 7d               | Recommended if you widen it        |
| `popular`           | 7d               | Recommended if you widen it        |
| `interest`          | 2d               | Recommended if you widen it        |

`current_feed` supports richer filters (`search_data`, `text`, `near`) that force read-time computation: the path a cutoff protects.

## How to set a cutoff

Set `cutoff_window` on the selector: a relative duration ("the last N ..."). Units: `s`, `m`, `h`, `d`, `w`, `y` (for example `"12h"`, `"7d"`, `"2w"`); minimum 1 hour.

```csharp label="C#"
// Bound a filtered current_feed scan to the last 14 days.
var response = await _feedsV3Client.CreateFeedGroupAsync(new CreateFeedGroupRequest
{
    ID = "team_updates",
    ActivitySelectors = new List<ActivitySelectorConfig>
    {
        new()
        {
            Type = "current_feed",
            Filter = new Dictionary<string, object>
            {
                ["search_data"] = new Dictionary<string, object>
                {
                    ["$contains"] = new Dictionary<string, object>
                    {
                        ["category"] = "announcement"
                    }
                }
            },
            CutoffWindow = "14d"
        }
    }
});
```

## Choosing a window

- Match scroll depth: `7d` to `14d` suits most hot feeds; keep older content in search or an archive.
- Narrower filters need shorter windows.
- Start conservative, widen later if needed.

>
> **Warning:** Set a `cutoff_window` on filtered read-time selectors before production: `current_feed`, `query`, `proximity`, and `follow_suggestion`.
>

---

For the most recent version of this documentation, visit [https://getstream.io/activity-feeds/docs/dotnet-csharp/cutoff-date/](https://getstream.io/activity-feeds/docs/dotnet-csharp/cutoff-date/).