Clone massive tables instantly and experiment safely in ClickHouse

ClickHouse offers a feature that allows users to create instant, zero-copy clones of production tables, enabling safe experimentation without affecting the original data. This process, akin to a Git fork, is made possible by ClickHouse's immutable data storage model, where every data insertion results in a new, self-contained part on disk. The cloning mechanism relies on hard-linking the column files from the source table to the cloned table, ensuring that the clone starts as an exact replica and diverges only upon modification. This part-level copy-on-write approach ensures that changes are isolated to specific parts, reducing storage overhead and maintaining high performance. The feature is particularly useful for testing destructive changes, schema experiments, and backfills, as it allows for rapid table replication independent of table size. In ClickHouse Cloud, cloned tables can be managed with isolated compute resources, further protecting the production environment while allowing users to explore the platform's capabilities with minimal risk.