Alerting on numeric data

This topic describes how Grafana handles alerting on numeric rather than time series data.

Among certain data sources numeric data that is not time series can be directly alerted on, or passed into Server Side Expressions (SSE). This allows for more processing and resulting efficiency within the data source, and it can also simplify alert rules. When alerting on numeric data instead of time series data, there is no need to reduce each labeled time series into a single number. Instead labeled numbers are returned to Grafana instead.

Tabular Data

This feature is supported with backend data sources that query tabular data:

A query with Grafana managed alerts or SSE is considered numeric with these data sources, if:

If there are string columns, then those columns become labels. The name of column becomes the label name, and the value for each row becomes the value of the corresponding label. If multiple rows are returned, then each row should be uniquely identified their labels.

Example

For a MySQL table called “DiskSpace”:

You can query the data filtering on time, but without returning the time series to Grafana. For example, an alert that would trigger per Host, Disk when there is less than 5% free space:

SELECT Host , Disk , CASE WHEN PercentFree  < 5.0 THEN PercentFree  ELSE 0 END FROM ( 
   SELECT
      Host, 
      Disk, 
      Avg(PercentFree) 
   FROM DiskSpace
   Group By
      Host, 
      Disk 
   Where __timeFilter(Time)

This query returns the following Table response to Grafana:

When this query is used as the condition in an alert rule, then the non-zero will be alerting. As a result, three alert instances are produced: