v.25.6Improvement

Setting use_skip_indexes_if_final and use_skip_indexes_if_final_exact_mode now default

Official CH changelog text
Setting use_skip_indexes_if_final and use_skip_indexes_if_final_exact_mode now default to True. Queries with FINAL clause will now use skip indexes (if applicable) to shortlist granules and also read any additional granules corresponding to matching primary key ranges. Users needing earlier behaviour of approximate/imprecise results can set use_skip_indexes_if_final_exact_mode to FALSE after careful evaluation. #81331 (Shankar Iyer).
The settings use_skip_indexes_if_final and use_skip_indexes_if_final_exact_mode now default to True, enabling queries with the FINAL clause to utilize skip indexes for more precise granule selection.

Why it matters

This feature improves query accuracy when using the FINAL clause by leveraging skip indexes to shortlist granules and also reading additional granules based on matching primary key ranges. It addresses the issue of approximate or imprecise results in FINAL queries by defaulting to a more exact and reliable index usage.

How to use it

Since these settings default to True, queries with the FINAL clause automatically benefit from skip indexes. Users who prefer the earlier behavior with approximate results can set use_skip_indexes_if_final_exact_mode = FALSE in the server configuration or query context after evaluation.

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