Support for ATTACH TABLE ... ON CLUSTER Queries

Why it matters

This feature enables users to attach existing tables simultaneously on all nodes within a specified cluster, simplifying cluster-wide table management and ensuring consistency across distributed ClickHouse setups.

How to use it

Use the ATTACH TABLE ... ON CLUSTER <cluster_name> syntax to attach tables on all nodes of the specified cluster. For example:

ATTACH TABLE my_table ON CLUSTER my_cluster;