Explore the importance of PromQL compatibility testing in this conference talk by Julius Volz, co-founder of Prometheus. Dive into the challenges of implementing PromQL across various platforms and the need for standardization in the Prometheus ecosystem. Learn about an open-source PromQL compliance testing suite designed to evaluate and compare different implementations. Discover test results from actual vendor PromQL implementations, analyze behavioral differences, and gain insights into recommendations for implementing PromQL in products or services. Understand the implications of compatibility issues on user experience, ecosystem fragmentation, and potential vendor lock-in. Get an overview of various PromQL implementations, including Chronosphere, M3, Fire, New Relic, and Promscale, and learn how to interpret test scores for informed decision-making.