Understanding Transaction Bugs in Database Systems

Transactions are used to guarantee data consistency and integrity in Database Management Systems (DBMSs), and have become an indispensable component in DBMSs. However, faulty designs and implementations of DBMSs' transaction processing mechanisms can introduce transaction bugs, and lead to severe consequences, e.g., incorrect database states and DBMS crashes. An in-depth understanding of real-world transaction bugs can significantly promote effective techniques in combating transaction bugs in DBMSs. In this paper, we conduct the first comprehensive study on 140 transaction bugs collected from six widely-used DBMSs, i.e., MySQL, PostgreSQL, SQLite, MariaDB, CockroachDB, and TiDB. We investigate these bugs from their bug manifestations, root causes, bug impacts and bug fixing. Our study reveals many in-teresting findings and provides useful guidance for transaction bug detection, testing, and verification.