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Add Settings for Execution Time and Timeout Behavior in Distributed Queries

Add a setting max_execution_time_leaf to limit the execution time on shard for distributed query, and timeout_overflow_mode_leaf to control the behaviour if timeout happens. #51823 (Duc Canh Le).
Introduces the max_execution_time_leaf setting to limit the execution time on individual shards during distributed queries, along with timeout_overflow_mode_leaf to control the behavior when such a timeout occurs.

Why it matters

This feature addresses the need to manage and control execution time limits more granularly on shards in distributed queries. It helps prevent long-running operations on shards from delaying the entire distributed query, improving query reliability and resource management.

How to use it

Set the max_execution_time_leaf setting to specify the maximum allowed execution time on each shard during a distributed query. Use the timeout_overflow_mode_leaf setting to define how the system should behave if a shard's execution time exceeds the limit (e.g., to abort or continue the query). These settings can be adjusted per session or query to fine-tune distributed execution time management.