v.25.12New Feature

Support ZooKeeper persistent watches

Support for ZooKeeper persistent watches in ClickHouse Keeper. Continuation part 2: https://github.com/ClickHouse/ClickHouse/pull/78207. #88813 (Konstantin Vedernikov).
Added support for ZooKeeper persistent watches in ClickHouse Keeper, enabling more reliable and efficient watch management.

Why it matters

This feature enhances ClickHouse Keeper by introducing persistent watches, which remain active until explicitly removed. This solves the problem of ephemeral watches that get lost after client reconnection, improving consistency and reducing the need for clients to repeatedly re-register watches.

How to use it

Users can enable ZooKeeper persistent watches by using the new persistent watch API in ClickHouse Keeper. Watches can be created and managed through the Keeper interface, allowing clients to set persistent watches that survive client session interruptions.