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Graph Directed Locking
February 1988 (vol. 14 no. 2)
pp. 133-140

A non-two-phase database concurrency control technique is introduced. The technique is deadlock-free, places no restrictions on the structure of the data, never requires data to be reread, never forces a transaction to be rolled back in order to achieve serializability, applies a type of lock conversion, and allows items to be released to subsequent transactions as soon as possible. The method introduced, database flow graph locking (FGL), uses a directed acyclic graph to direct the migration of locks between transactions. Unlike many previous non-two-phase methods, the database need not be structured in any specific fashion. The effect of these changes is that, with the same serializable schedule, FGL obtains a higher degree of concurrency than two-phase locking (2PL). Overhead requirements for database flow graph locking are comparable to those for two-phase locking, with 2PL being better in low conflict situations and FGL better in high conflict.

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Index Terms:
distributed databases; database concurrency control; deadlock-free; lock conversion; database flow graph locking; directed acyclic graph; non-two-phase methods; database theory; directed graphs; distributed databases; system recovery
M.H. Eich, "Graph Directed Locking," IEEE Transactions on Software Engineering, vol. 14, no. 2, pp. 133-140, Feb. 1988, doi:10.1109/32.4633
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