v.21.9Improvement

Add MaxPushedDDLEntryID Metric for Zookeeper Integration

Add a new metric called MaxPushedDDLEntryID which is the maximum ddl entry id that current node push to zookeeper. #27174 (Fuwang Hu).
Introduces a new metric MaxPushedDDLEntryID that tracks the maximum DDL entry ID pushed by the current ClickHouse node to ZooKeeper.

Why it matters

This metric helps monitor and debug DDL (Data Definition Language) replication by providing visibility into the highest DDL entry ID that the node has pushed to ZooKeeper, ensuring consistency and aiding in troubleshooting synchronization issues.

How to use it

The MaxPushedDDLEntryID metric is available immediately after the update and can be accessed through the node's metrics endpoint or monitoring tools querying the system metrics. No additional configuration is required to enable this metric.