v.25.12Experimental Feature
Automatic parallel replicas execution
The new logic is introduced to automatically execute queries using parallel replicas, controlled by the setting automatic_parallel_replicas_mode. During normal single-node execution, ClickHouse collects statistics that will later be considered during the planning stage. If statistics suggest that parallel replicas are likely to be beneficial, ClickHouse will automatically execute the given query with parallel replicas. The set of supported queries is currently fairly limited. #87541 (Nikita Taranov).Why it matters
This feature aims to optimize query execution by automatically deciding when to run queries using parallel replicas based on collected runtime statistics. It resolves the inefficiency of single-node query processing by distributing workload across replicas, potentially improving performance without manual intervention.How to use it
Users can enable automatic parallel replicas execution by settingautomatic_parallel_replicas_mode to on or appropriate mode. ClickHouse will then monitor query statistics and automatically run supported queries in parallel across replicas when advantageous.