Data Quality Metrics

Telmai enables users to monitor a wide range of data quality metrics and receive alerts when anomalies or issues are detected. Alerts serve as warnings that something may not be as expected. Some alerts can be configured to trigger notifications, while others are displayed in the Telmai UI for informational purposes. Additionally, some alerts may initiate remediation actions, such as segregating good data from bad, triggering a circuit breaker for the pipeline, and more.

What is monitored?

1. Out-of-the-Box Metrics: Telmai automatically monitors a variety of metrics related to table metadata and Health KPIs(mentioned in Data Health KPIs)

2. Custom Metrics: Users can define their own metrics to monitor specific data quality concerns.

Each monitored metric is validated against a set of policies, which define thresholds, scope, notification settings, and more. If a metric violates a policy, an alert is generated. The flow diagram below illustrates how alerts are created.

• Record Level Freshness: Percentage of outdated records in the scan, based on defined freshness criteria

• Table Level Freshness: Time elapsed since the last change in the monitored table at the time of the scan

• Record Count: Number of records being scanned

• Total Table Records Count: Total number of records in the monitored table. This may be larger than the record count if the scan involves only a subset of data, such as when delta detection is configured

• Correctness: Percentage of records that meet defined data quality rules

• Completeness: Percentage of records with non-null/missing values

• Record ID Uniqueness: Percentage of unique records based on the configured ID attribute.

• Uniqueness: Percentage of unique values within an attribute

User Defined Metrics

Users can create custom metrics to track specific anomalies. To add a new custom metric:

1. Select the Dataset: Choose the dataset you want to monitor

2. Navigate to “Alerting Policies”: Go to the “Metrics” tab

3. Add a Custom Metric:

   • Click the “+ Custom Metric” button

   • A new window will open, allowing you to define the metric

4. Define the Metric:

   • Name: Enter a name for the metric

   • Description: Provide a brief explanation of the metric

   • Aggregation: Select an aggregation function (e.g., SUM, AVG)

   • Attribute: Choose the column to be used for aggregation

   • Group By: Select a grouping attribute, or choose “None” if grouping is not required

   • Click Create to save the metric

Telmai will start monitoring this metric in future scans Important: Defining a metric here makes it available for tracking and alerting. However, no alerts will be generated until a policy is created using this metric.