In the domain of high-performance database management, a fundamental and persistent tension exists between two critical objectives: guaranteeing absolute data integrity and maximizing transactional throughput. The primary mechanism for ensuring integrity is locking, a process that serializes access to data resources to prevent conflicts. However, the very act of locking introduces the potential for contention, where one process must wait for another to release a resource, thereby impeding the goal of high concurrency.

Early architectural challenges, such as the performance bottleneck of index page locking, were resolved through significant design changes like the introduction of Type 2 indexes in Db2 Version 4. As systems scaled and the sheer volume of lock requests became a performance concern in itself, Db2 introduced sophisticated lock avoidance techniques to reduce the CPU overhead of the locking process without compromising integrity.

With the release of Db2 13 for z/OS, this evolutionary path continues. The focus has shifted to addressing a more nuanced problem prevalent in modern online transaction processing (OLTP) environments: the impact of transient lock contention. In high-volume systems, it is common for a resource to be locked for mere milliseconds by a concurrent utility or another short transaction. In previous versions of Db2, such a momentary conflict during an INSERT operation into a Partition-by-Growth (PBG) tablespace could trigger an immediate and irreversible transaction failure. This behavior, while safe, was inefficient, pushing the burden of retry logic onto the application layer and artificially depressing system throughput.