# RateOfChangeAlertConfig
**Source definition:** [`src/bitdrift/public/unary/alerts/v1/alerts.proto#L116-L152`]()
Rate of change alerts are used to look at significant changes over a period of time. They work
for counter, rate, and histogram chart types.
| Field | Type | Description |
|---|---|---|
| window | [google.protobuf.Duration](https://protobuf.dev/reference/protobuf/google.protobuf/#duration "google.protobuf.Duration") | This comparison type defines a window. [now - window, now] is compared to [now - 2 * window, now - window]. |
| absolute_change | doubleonly one of absolute_change, or percentage_change can be set | This compares an absolute amount of change when the data is aggregated across each of the comparison windows. |
| percentage_change | doubleonly one of percentage_change, or absolute_change can be set | This compares a percentage of change when the data is aggregated across each of the comparison windows. |
| change_direction | [bitdrift.public.unary.alerts.v1.RateOfChangeAlertConfig.ChangeDirection](#bitdrift.public.unary.alerts.v1.RateOfChangeAlertConfig.ChangeDirection "bitdrift.public.unary.alerts.v1.RateOfChangeAlertConfig.ChangeDirection")
must be a defined enum value | The direction of change to check for. |
| histogram_configuration | [bitdrift.public.unary.charts.v1.HistogramConfiguration](bitdrift_public_unary_charts_v1_HistogramConfiguration.md "bitdrift.public.unary.charts.v1.HistogramConfiguration") | Configuration for any histogram values within the aggregate ID. This is required if the aggregate ID refers to a histogram so that one or more percentiles can be used as part of the alert condition. |
| limit_strategy | [bitdrift.public.unary.charts.v1.LimitStrategy](bitdrift_public_unary_charts_v1_LimitStrategy.md "bitdrift.public.unary.charts.v1.LimitStrategy") | Optional limit strategy to use for this alert. If this is omitted, a default value of limiting by a top k of 5 entries is used. Ultimately this will allow alerting on specific dimensions for a group by aggregate ID if desired. |
Example
```json
{
"absolute_change": 100.0,
"change_direction": "INCREASE",
"histogram_configuration": {
"percentile": 1.0,
"percentiles": [
1.0
]
},
"limit_strategy": {
"exclusions": {
"dimension_identifiers": [
{
"id": "time_series_id_opaque_example",
"labels": [
{
"name": "name",
"value": "value"
}
]
}
],
"return_other": false
},
"sort_order": "MAX",
"top_k_limit": {
"top_k": 5
}
},
"window": "3600s"
}
```
# RateOfChangeAlertConfig.ChangeDirection Enum
**Source definition:** [`src/bitdrift/public/unary/alerts/v1/alerts.proto#L117-L120`]()
| Name | Description |
|---|---|
| INCREASE | |
| DECREASE | |