v.25.8Improvement

Joins with parallel replicas now use

Official CH changelog text
Joins with parallel replicas now use the join logical step. In case of any issues with join queries using parallel replicas, try SET query_plan_use_new_logical_join_step=0 and report an issue. #83801 (Vladimir Cherkasov).
Joins involving parallel replicas now utilize the new join logical step in the query execution plan.

Why it matters

This feature improves the processing of join queries executed with parallel replicas by using a new logical step, which aims to enhance performance and reliability. It addresses issues in join queries that arise when parallel replicas are involved.

How to use it

The new logical join step is enabled by default for joins with parallel replicas. If you encounter problems with join queries under parallel replicas, you can temporarily disable the new join logical step by running: 
SET query_plan_use_new_logical_join_step=0
. You are encouraged to report any issues encountered.

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