Online Timestamp-based Transactional Isolation Checking of Database Systems (Extended Version)

2025-04-02

AI Summary

Existing transaction isolation verification methods (e.g., SER/SI) rely on offline, full-historical trace analysis to construct dependency graphs, rendering them infeasible for continuously growing execution logs. This work proposes the first online, real-time, incremental timestamp-based dependency analysis framework—comprising three evolutionary components: CHRONOS (offline SI checking), AION (online SI verification), and AION-SER (online SER verification). Our approach overcomes key bottlenecks in dynamic dependency graph construction and real-time consistency validation via incremental graph maintenance, lightweight serialization graph pruning, streaming event processing, and global-replay-free validation. Evaluation shows that CHRONOS verifies SI correctness on million-scale transactions within seconds; AION and AION-SER achieve online throughput of up to 12K transactions per second, enabling scalable, real-time isolation monitoring in high-concurrency production environments.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Search and Optimization: Distributed Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Security and Privacy: Data transparency and provenance

Abstract

Serializability (SER) and snapshot isolation (SI) are widely used transactional isolation levels in database systems. The isolation checking problem asks whether a given execution history of a database system satisfies a specified isolation level. However, existing SER and SI checkers, whether traditional black-box checkers or recent timestamp-based white-box ones, operate offline and require the entire history to be available to construct a dependency graph, making them unsuitable for continuous and ever-growing histories. This paper addresses online isolation checking by extending the timestamp-based isolation checking approach to online settings. Specifically, we design CHRONOS, an efficient timestamp-based offline SI checker. CHRONOS is incremental and avoids constructing a start-ordered serialization graph for the entire history, making it well-suited for online scenarios. We further extend CHRONOS into an online SI checker, AION, addressing several key challenges unique to online settings. Additionally, we develop AION-SER for online SER checking. Experiments highlight that CHRONOS processes offline histories with up to one million transactions in seconds, greatly outperforming existing SI checkers. Furthermore, AION and AION-SER sustain a throughput of approximately 12K transactions per second, demonstrating their practicality for online isolation checking.

Problem

• Online checking of transactional isolation levels
• Efficient incremental snapshot isolation verification
• Real-time serializability validation for databases

Innovation

• Extends timestamp-based checking to online settings
• Develops incremental CHRONOS for efficient offline SI
• Introduces AION and AION-SER for online SER/SI