TimescaleDB Data retention policy not working

What is TimescaleDB Data retention policy not working

Understanding TimescaleDB

TimescaleDB is an open-source time-series database optimized for fast ingest and complex queries. It is built on top of PostgreSQL, providing the reliability and robustness of PostgreSQL while adding time-series specific features. One of its key features is the ability to manage data retention policies, which helps in automatically removing old data that is no longer needed, thus saving storage space and improving performance.

Identifying the Symptom

When working with TimescaleDB, you might encounter an issue where the data retention policy is not functioning as expected. This can manifest as old data not being deleted according to the defined retention policy, leading to increased storage usage and potentially degraded performance.

Exploring the Issue

The issue, identified as TSDB-008, typically arises when the retention policy is not properly configured or the retention job is not running. TimescaleDB uses background workers to execute retention policies, and any misconfiguration can prevent these jobs from executing correctly.

Common Causes

The retention policy might not be set up correctly in the database. The background worker responsible for executing the retention policy might not be active.

Steps to Fix the Issue

To resolve the issue of a non-working data retention policy in TimescaleDB, follow these steps:

Step 1: Verify Retention Policy Configuration

First, ensure that the retention policy is correctly configured. You can check the existing policies using the following SQL query:

SELECT * FROM timescaledb_information.jobs WHERE proc_name = 'policy_retention';

This query will list all retention policies. Verify that the policy is set for the correct hypertable and with the desired retention period.

Step 2: Check Background Worker Status

Next, ensure that the background worker responsible for executing the retention policy is running. You can check the status of background workers with:

SELECT * FROM pg_stat_activity WHERE application_name = 'TimescaleDB Background Worker';

If the worker is not running, you may need to restart the database or check the database logs for any errors related to background workers.

Step 3: Adjust Configuration if Necessary

If the retention policy is not configured correctly, you can adjust it using the add_retention_policy function. For example:

SELECT add_retention_policy('your_hypertable', INTERVAL '30 days');

This command sets a retention policy to keep data for 30 days.

Additional Resources

For more detailed information on configuring and troubleshooting retention policies in TimescaleDB, refer to the official TimescaleDB documentation on data retention. Additionally, the background tasks documentation provides insights into managing background workers.

By following these steps, you should be able to resolve the issue of a non-working data retention policy in TimescaleDB, ensuring your database remains efficient and well-maintained.