> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fluidify.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Deduplication

# Alert Deduplication & Grouping

Regen prevents alert storms from creating hundreds of duplicate incidents. Two mechanisms work together: **deduplication** (same alert firing again) and **grouping** (different alerts that belong to the same incident).

## Deduplication

When an alert arrives, Regen checks if an active alert with the same `external_id` already exists:

* **Match found** — Regen updates the existing alert (timestamps, annotations). No new alert or incident is created.
* **No match** — Regen creates a new alert and evaluates routing rules.

The `external_id` source depends on the integration:

| Source     | ExternalID used                 |
| ---------- | ------------------------------- |
| Prometheus | `fingerprint` field             |
| Grafana    | `fingerprint` field             |
| CloudWatch | `AlarmArn`                      |
| Generic    | `external_id` field you provide |

## Grouping Rules

Grouping combines multiple related alerts into a single incident. Configure under **Settings → Grouping Rules**.

### Example: Group all alerts from the same service

```
Match labels:  service = payments-api
Group by:      service
Window:        5 minutes
```

If `payments-api` fires three different alerts within 5 minutes, Regen creates one incident and links all three alerts to it.

### How it works

1. A new alert arrives
2. Regen checks active grouping rules in priority order
3. If a rule matches, Regen looks for an open incident that already has alerts matching the same group key
4. **Match found** — the alert is linked to the existing incident (no new incident created)
5. **No match** — evaluated against routing rules to determine whether to create a new incident

### Grouping rule fields

| Field        | Description                                                                                           |
| ------------ | ----------------------------------------------------------------------------------------------------- |
| Name         | Human-readable label                                                                                  |
| Match labels | Conditions that must match for this rule to apply (key=value pairs)                                   |
| Group by     | Label keys used to compute the group key                                                              |
| Window       | Time window — alerts in the same group that arrive within this window are linked to the same incident |
| Priority     | Lower number = evaluated first                                                                        |

## Routing Rules

Routing rules control what happens after deduplication and grouping. Configure under **Settings → Routing Rules**.

Rules are evaluated in priority order. The first matching rule wins. Match criteria support exact matching, RE2 regex on label/annotation values, and `*` wildcards.

→ **Full reference:** [Alert Routing Rules](routing.md)