Monitor Update Queue Size in Cache via System Metrics

Why it matters

This feature provides visibility into the internal update queues of dictionary caches, allowing users to monitor the queue sizes and better understand the performance and behavior of dictionary updates. It helps in diagnosing bottlenecks or delays in dictionary refresh processes.

How to use it

Users can monitor the update queue size by querying the relevant system metrics exposed by ClickHouse. No additional configuration is needed; the metrics for cache and complex_key_cache dictionaries are available in the system metrics once the dictionaries are being used.