The same alert can potentially trigger many times over a short period of time. If it is set to send out notifications, it can swamp your channels and get too noisy.
To avoid this problem, you can add a waiting period between alert notifications from anywhere between 5 minutes to 24 hours.
Alert's escalations and de-escalations configuration
If you add a waiting period between notifications, they do not delay notifications of escalations or de-escalations.
If you have several thresholds with different severities configured for an alert, each is evaluated independently. If the same alert triggers multiple times within the waiting period but for different thresholds, a notification for each threshold is sent out without waiting.
Group alert triggers by fields
If an alert includes group-by fields, it will be evaluated independently per set of results.
When you group results by a field, you are taking the log results and dividing them into groups (i.e. "buckets" in OpenSearch Dashboards terminology) by the values returned for that field. That is, each value or set of values is considered a separate event.
If the same alert triggers multiple times within the waiting period but for different values, the notifications will be sent out without delay. In other words, the waiting period will only affect notifications for the exact same set of group by results.
For example, let's take an alert that groups results by city. This alert will trigger per city or set of cities. If this alert triggers for
Paris and London and
Paris, London, and Berlin, both alerts will be sent without waiting because they triggered for different values.