Predicate Derivation and Monotonicity Detection in DB2 UDB
Bibliographic record
Abstract
DB2 universal database allows database schema designers to specify generated columns. These generated columns are useful for maintaining rollup hierarchy variables in warehouses (e.g., date, month, quarter). In order for the generated columns to be useful for query processing, queries must automatically make use of such columns when applicable. In particular, query predicates on the original columns should be rewritten to make use of the generated columns. In this paper, we describe two main aspects of this predicate rewriting technique that allows usage of the generated columns for a variety of query predicate types. The first aspect, monotonicity detection, allows for rewrites in the case of range predicates. The second aspect, predicate derivation, is the technique for using generating expressions for query processing. We show the value of this technique for providing significant performance improvement when combined with indexing or multidimensional clustering in DB2.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.018 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.005 | 0.006 |
| Open science | 0.003 | 0.005 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".