v.23.11Improvement
Deduplicate Requests to ZooKeeper from Concurrent Queries in system.replicas
Queries tosystem.replicasinitiate requests to ZooKeeper when certain columns are queried. When there are thousands of tables these requests might produce a considerable load on ZooKeeper. If there are multiple simultaneous queries tosystem.replicasthey do same requests multiple times. The change is to "deduplicate" requests from concurrent queries. #56420 (Alexander Gololobov).
Why it matters
Queries tosystem.replicas trigger ZooKeeper requests for certain columns which can cause significant load when thousands of tables exist. Multiple simultaneous queries cause repeated identical requests, increasing ZooKeeper load unnecessarily. This feature reduces ZooKeeper overhead by deduplicating requests from concurrent queries, improving performance and stability under heavy system.replicas query load.How to use it
This improvement is applied automatically to all queries accessingsystem.replicas. No special configuration or user action is required to enable the deduplication of requests to ZooKeeper.