v.22.5Experimental Feature

Improved Communication for Localhost Replica in Parallel Queries

Official CH changelog text
Improvement for parallel replicas: We create a local interpreter if we want to execute query on localhost replica. But for when executing query on multiple replicas we rely on the fact that a connection exists so replicas can talk to coordinator. It is now improved and localhost replica can talk to coordinator directly in the same process. #36281 (Nikita Mikhaylov).
Improved communication between localhost replica and coordinator in parallel replication queries by enabling direct in-process interaction.

Why it matters

Previously, when executing queries on multiple replicas, communication between replicas and the coordinator required existing connections, limiting efficiency for localhost replicas. This feature enhances the parallel replicas mechanism by allowing the localhost replica to communicate directly with the coordinator within the same process, improving performance and reliability.

How to use it

This improvement is applied automatically when executing queries on multiple replicas involving the localhost replica, requiring no additional user configuration.

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