Support for Processors (new Query Execution Pipeline) in Mergetree

Why it matters

This feature introduces a new, more efficient query execution pipeline called processors to MergeTree tables, enabling improved query performance and resource utilization during data processing.

How to use it

The new processor-based execution pipeline is integrated into MergeTree tables and activates automatically when using the latest ClickHouse version after the upgrade. Users do not need to make manual changes to enable this feature.