v.21.7New Feature

Add prefer_global_in_and_join boolean setting for IN/JOIN operations

Add a new boolean setting prefer_global_in_and_join which defaults all IN/JOIN as GLOBAL IN/JOIN. #23434 (Amos Bird).
Introduces a new boolean setting prefer_global_in_and_join that defaults all IN and JOIN operations to their global variants (GLOBAL IN and GLOBAL JOIN).

Why it matters

This setting addresses the need to optimize query execution in distributed environments by preferring global joins and IN operations by default, which can improve query performance and consistency when working with distributed tables.

How to use it

Enable the feature by setting prefer_global_in_and_join = 1 in the ClickHouse server configuration or per session. Once enabled, all IN and JOIN clauses will implicitly use the global variant without needing to specify GLOBAL explicitly in queries.