> ## Documentation Index > Fetch the complete documentation index at: https://elementary-more-explicit-webhook-instructions.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # event_freshness_anomalies `elementary.event_freshness_anomalies` Monitors the freshness of event data over time, as the expected time it takes each event to load - that is, the time between when the event actually occurs (the `event timestamp`), and when it is loaded to the database (the `update timestamp`). This test compliments the `freshness_anomalies` test and is primarily intended for data that is updated in a continuous / streaming fashion. The test can work in a couple of modes: * If only an `event_timestamp_column` is supplied, the test measures over time the difference between the current timestamp ("now") and the most recent event timestamp. * If both an `event_timestamp_column` and an `update_timestamp_column` are provided, the test will measure over time the difference between these two columns. ### Test configuration *Required configuration: `event_timestamp_column`* *Default configuration: `anomaly_direction: spike` to alert only on delays.* {/* prettier-ignore */} 
  
    tests:
      -- elementary.event\_freshness\_anomalies:
        event\_timestamp\_column: column name
        update\_timestamp\_column: column name
        where\_expression: sql expression
        anomaly\_sensitivity: int
        detection\_period:
          period: \[hour | day | week | month]
          count: int
        training\_period:
          period: \[hour | day | week | month]
          count: int
        time\_bucket:
          period: \[hour | day | week | month]
          count: int
        seasonality: day\_of\_week
        detection\_delay:
          period: \[hour | day | week | month]
          count: int
        ignore\_small\_changes:
          spike\_failure\_percent\_threshold: int
          drop\_failure\_percent\_threshold: int
        anomaly\_exclude\_metrics: \[SQL expression]
```yml Models models: - name: < model name > tests: - elementary.event_freshness_anomalies: event_timestamp_column: < timestamp column > # Mandatory update_timestamp_column: < timestamp column > # Optional where_expression: < sql expression > time_bucket: # Daily by default period: < time period > count: < number of periods > ``` ```yml Models example models: - name: login_events tests: - elementary.event_freshness_anomalies: event_timestamp_column: "occurred_at" update_timestamp_column: "updated_at" # optional - use tags to run elementary tests on a dedicated run tags: ["elementary"] config: # optional - change severity severity: warn ```