Detecting absence: querying for the events that never happened

This article discusses Drasi, a CNCF Sandbox project for continuous queries over changing data, focusing on detecting absence—events that never happened. The author contrasts traditional polling methods (timer-triggered functions, state tables, dedup logic) with Drasi's standing queries that maintain current results continuously. Key features include temporal functions like trueFor, trueLater, and trueUntil, which simplify absence detection. The author tests Drasi against AKS and Azure Database for PostgreSQL, noting the slidingWindow function is not yet available in version 0.10.0. The article highlights how Drasi reduces infrastructure complexity and improves responsiveness.