Deadlock freedom using edge locks
ACM Transactions on Database Systems (TODS)
Consistency in Hierarchical Database Systems
Journal of the ACM (JACM)
A Theory of Safe Locking Policies in Database Systems
Journal of the ACM (JACM)
Locking Primitives in a Database System
Journal of the ACM (JACM)
Locking Protocols: From Exclusive to Shared Locks
Journal of the ACM (JACM)
The notions of consistency and predicate locks in a database system
Communications of the ACM
Concurrent one-way protocols in around-the-clock social networks
Procceedings of the 13th International Workshop on the Web and Databases
Concurrent atomic protocols for making and changing decisions in social networks
CIKM '10 Proceedings of the 19th ACM international conference on Information and knowledge management
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A large number of locking protocols use precedence relations among data items to ensure the serializability of the database system. These protocols have extended the semantics of the exclusive lock from prohibiting access to a data item to prohibiting access to an entire subgraph. In this paper we argue that combining the use of exclusive locks for these different purposes is ill conceived. We present a general theory on how these two distinct functions can be separated into the traditional locks operating on the individual data items, and a corresponding set operating on the edges of graph. This is illustrated by a general transformation from a given graph protocol to the new edge protocol which preserves the major properties of the original protocol. We then give a characterization for a large class of edge lock protocols within a database system, which includes most previous locking protocols defined on databases organized as graphs. We show how this separation increases concurrency, and generalizes previously unrelated concepts, such as using deadlock avoidance locks in general locking protocols.