v.23.5Improvement

Cluster Table Functions to Skip Unavailable Shards

Cluster table functions should always skip unavailable shards. close #46314. #46765 (zk_kiger).
Cluster table functions in ClickHouse now automatically skip shards that are unavailable during query execution.

Why it matters

This feature improves query reliability and fault tolerance by ensuring that queries using cluster table functions do not fail or hang due to unreachable or offline shards. It provides a smoother user experience in distributed environments where shard availability can vary.

How to use it

No explicit user action is required to enable this behavior. When using cluster table functions, ClickHouse will internally skip any unavailable shards to complete the query.