v.25.12Improvement
Fix potential thread pool starvation
Fixed potential thread pool starvation when reading column samples for JSON columns with many subcolumns by respecting the merge_tree_use_prefixes_deserialization_thread_pool setting instead of unconditionally using the thread pool. #91208 (Raufs Dunamalijevs).Why it matters
This fix addresses potential thread pool starvation caused by unconditionally using the thread pool during deserialization of JSON columns with many subcolumns. By respecting the existingmerge_tree_use_prefixes_deserialization_thread_pool setting, it ensures more efficient resource usage and prevents performance degradation.How to use it
Ensure themerge_tree_use_prefixes_deserialization_thread_pool setting is configured appropriately to control whether the thread pool is used during prefixes deserialization for MergeTree tables when reading JSON columns. The fix makes the process respect this setting automatically.