v.21.7New Feature

Restoration of Replicated Tables with Lost ZooKeeper Metadata

Provides a way to restore replicated table when the data is (possibly) present, but the ZooKeeper metadata is lost. Resolves #13458. #13652 (Mike Kot).
Introduces a method to restore a replicated table in ClickHouse when the underlying data is present but the ZooKeeper metadata has been lost.

Why it matters

This feature addresses the problem of losing ZooKeeper metadata for replicated tables while the actual data files remain intact. It allows users to recover and restore the replicated table without needing to reinsert or recalculate data, thus minimizing downtime and data inconsistency.

How to use it

Users can invoke the new restoration method to rebuild ZooKeeper metadata from existing data on disk for the replicated table. This process helps synchronize the table state without requiring a full resynchronization or data reload.