Fast Verification of Strong Database Isolation (Extended Version)

2025-11-17

AI Summary

Verifying strong database isolation (e.g., serializability, snapshot isolation) in black-box settings is hindered by uncertain transaction dependencies and limited observable behavior. This paper introduces *hyper-polygraphs*, a formal framework that uniformly models both deterministic and uncertain dependencies among transactions. Our approach integrates load-aware SMT encoding optimizations, static analysis, and constraint simplification to achieve high-precision, scalable anomaly detection. Evaluated on standard benchmarks—including TPC-C and SmallBank—our method supports larger, more general workloads than prior tools, accurately identifies diverse isolation anomalies (e.g., write-skew, anti-dependency cycles), and improves verification efficiency by one to two orders of magnitude. To the best of our knowledge, this is the first technique enabling large-scale black-box isolation verification under uncertain dependencies.

Technology Category

• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories
• Data Mining & Knowledge Management: Anomaly/Outlier Detection
• Reasoning under Uncertainty: Stochastic Optimization

Application Category

• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Security and Privacy: Large-scale security measurements
• Web Mining and Content Analysis: Web data provenance, reliability, and authenticity

Abstract

Strong isolation guarantees, such as serializability and snapshot isolation, are essential for maintaining data consistency and integrity in modern databases. Verifying whether a database upholds its claimed guarantees is increasingly critical, as these guarantees form a contract between the vendor and its users. However, this task is challenging, particularly in black-box settings, where only observable system behavior is available and often involves uncertain dependencies between transactions. In this paper, we present VeriStrong, a fast verifier for strong database isolation. At its core is a novel formalism called hyper-polygraphs, which compactly captures both certain and uncertain transactional dependencies in database executions. Leveraging this formalism, we develop sound and complete encodings for verifying both serializability and snapshot isolation. To achieve high efficiency, VeriStrong tailors SMT solving to the characteristics of database workloads, in contrast to prior general-purpose approaches. Our extensive evaluation across diverse benchmarks shows that VeriStrong not only significantly outperforms state-of-the-art verifiers on the workloads they support, but also scales to large, general workloads beyond their reach, while maintaining high accuracy in detecting isolation anomalies.

Problem

• Verifying strong isolation guarantees in databases
• Addressing uncertain transactional dependencies in black-box settings
• Developing efficient verification for serializability and snapshot isolation

Innovation

• Introduces hyper-polygraphs for dependency modeling
• Develops SMT-based encodings for isolation verification
• Tailors SMT solving to database workload characteristics