Global Serializability - The Global Serializability Problem - Technology Perspective

Technology Perspective

The problem of global serializability has been a quite intensively researched subject in the late 1980s and early 1990s. Commitment ordering (CO) has provided an effective general solution to the problem, insight into it, and understanding about possible generalizations of strong strict two phase locking (SS2PL), which practically and almost exclusively has been utilized (in conjunction with the Two-phase commit protocol (2PC) ) since the 1980s to achieve global serializability across databases. An important side-benefit of CO is the automatic global deadlock resolution that it provides (this is applicable also to distributed SS2PL; though global deadlocks have been an important research subject for SS2PL, automatic resolution has been overlooked, except in the CO articles, until today (2009)). At that time quite many commercial database system types existed, many non-relational, and databases were relatively very small. Multi database systems were considered a key for database scalability by database systems interoperability, and global serializability was urgently needed. Since then the tremendous progress in computing power, storage, and communication networks, resulted in orders of magnitude increases in both centralized databases' sizes, transaction rates, and remote access to database capabilities, as well as blurring the boundaries between centralized computing and distributed one over fast, low-latency local networks (e.g., Infiniband). These, together with progress in database vendors' distributed solutions (primarily the popular SS2PL with 2PC based, a de facto standard that allows interoperability among different vendors' (SS2PL-based) databases; both SS2PL and 2PC technologies have gained substantial expertise and efficiency), workflow management systems, and database replication technology, in most cases have provided satisfactory and sometimes better information technology solutions without multi database atomic distributed transactions over databases with different concurrency control (bypassing the problem above). As a result, the sense of urgency that existed with the problem at that period, and in general with high-performance distributed atomic transactions over databases with different concurrency control types, has reduced. However, the need in concurrent distributed atomic transactions as a fundamental element of reliability exists in distributed systems also beyond database systems, and so the need in global serializability as a fundamental correctness criterion for such transactional systems (see also Distributed serializability in Serializability). With the proliferation of the Internet, Cloud computing, Grid computing, small, portable, powerful computing devices (e.g., smartphones), and sophisticated systems management the need for effective global serializability techniques to ensure correctness in and among distributed transactional applications seems to increase, and thus also the need in Commitment ordering (including the popular for databases special case SS2PL; SS2PL, though, does not meet the requirements of many other transactional objects).