SQL-RewriteBench: A Correctness-Gated, Full-Denominator Benchmark for Statement-Level SQL Rewriting [Experiment,Analysis & Benchmark]

2026-07-10

AI Summary

This work addresses a critical gap in existing SQL rewriting evaluation methodologies, which fail to holistically assess the end-to-end capabilities of deployable systems by neglecting the complete pipeline from input acceptance to the generation of correct, executable, and effective rewritten queries. To bridge this gap, the authors propose the first statement-level SQL rewriting benchmark framework, incorporating a correctness-gating mechanism and a comprehensive full-path evaluation metric that encompasses input acceptance, result consistency, execution success rate, and performance gain. Central to this framework are the Structured Context Sensitivity (SCS) index and the Correctness-Gated Optimization Quality (CGOQ) score, which uniquely treat result correctness as a prerequisite for performance improvement. Evaluation on a multidimensional dataset of 180 executable instances reveals that all seven state-of-the-art methods yield negative CGOQ scores, exposing pervasive deficiencies such as inadequate input handling, absent result validation, or ineffective optimization.

Abstract

Statement-level SQL rewriting can improve query performance and maintainability without changing the DBMS kernel, but existing benchmarks do not evaluate rewrite methods as deployable systems. They typically focus on DBMS performance, rule regression, query equivalence, or dialect translation, while missing the full path from accepting an input query to producing an executable, result-consistent, and operationally useful rewrite. We present SQL-RewriteBench, a benchmark for statement-level SQL rewriting that applies correctness gating and full-denominator accounting. Its metric suite explicitly separates Source Acceptance, Generation Rate, Execution Coverage, Result Consistency, UnsafeRewrite Rate, and speedup distribution. It also defines SCS, a deterministic index of static SQL structure, and CGOQ, a correctness-gated optimization-quality score that gives optimization credit only after the case-specific Checker Contract is satisfied. CGOQ combines runtime improvement with structural simplification through a continuous scoring function, making it suitable for deployment-oriented rewrite assessment. As an artifact, SQL-RewriteBench provides 180 executable Benchmark Instances organized into EQUIV, PERF, ROBUST, and DIALECT pools, each packaged with SQL, schema metadata, provenance, evidence, and rewrite-opportunity documentation. Across seven representative academic and LLM-based methods, every full-benchmark CGOQ is negative. Existing methods often fail before rewriting, fail result checks, or return correct rewrites that are slower or no better than the input. These results show that deployable SQL rewrite requires broader input handling, result validation, and benefit-aware rewrite decisions.

Problem

• SQL rewriting
• benchmark
• correctness
• deployable system
• query optimization

Innovation

• SQL rewriting
• correctness-gated benchmark
• CGOQ
• full-denominator evaluation
• deployable query optimization