Question

An IoT platform stores telemetry documents in a Cosmos DB for NoSQL container. The team wants most sensor readings to be automatically purged 30 days after creation to save storage costs, but a small subset of 'audit' documents must be retained indefinitely in the same container. Which configuration achieves this requirement with the least ongoing maintenance?

Accepted Answer

Set the container's DefaultTimeToLive to 2592000 (30 days), and set the item-level 'ttl' property to -1 on each audit document.

Answer

Set the container's DefaultTimeToLive to -1, and rely on a nightly stored procedure to delete non-audit documents older than 30 days.

Answer

Set the container's DefaultTimeToLive to null (off), and set the item-level 'ttl' property to 2592000 on each non-audit document.

Answer

Create two separate containers—one with DefaultTimeToLive of 2592000 for telemetry and one with TTL disabled for audit documents—and route writes accordingly.