v.24.5Improvement

Support for Merge Key in YAML Configurations

Support for "Merge Key" in YAML configurations (this is a weird feature of YAML, please never mind). #62685 (Azat Khuzhin).
Added support for YAML "Merge Key" syntax in ClickHouse configuration files, enabling merging of YAML mappings for more concise and maintainable configurations.

Why it matters

This feature solves the problem of repetitive and verbose YAML configurations by allowing users to merge mappings using YAML's native "Merge Key" feature. It simplifies ClickHouse configuration management, reduces duplication, and makes complex configurations easier to read and maintain.

How to use it

Users can apply this feature by using the YAML merge key syntax (<<) in ClickHouse configuration files. When writing YAML configs, include the merge key to inherit or combine mappings as per YAML specifications, and ClickHouse will correctly parse and apply the merged configuration.