v.25.10Improvement

Make query plan optimizations visible

Official CH changelog text
Make query plan optimizations visible to the correlated subquery input subplan by postponing it's materialization. Part of #79890. #85455 (Dmitry Novik).
Enhance query plan optimizations by postponing the materialization of correlated subquery input subplans to make optimizations visible and more effective.

Why it matters

This feature aims to improve query execution efficiency by allowing query plan optimizations to apply to the input subplan of correlated subqueries. By delaying materialization, the optimizer can produce better execution plans, leading to improved performance.

How to use it

No explicit user action is required. The enhancement is applied internally by the query optimizer to correlated subqueries automatically during query planning.

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