APPROACHES TO INCREASING DATABASE CONCURRENCY THROUGH LOCKING

Various locking protocols have been proposed for the purpose of allowing the safe concurrent access of a database. Each locking protocol defines a set of restrictions on the placement of lock and unlock steps within a transaction. We define further restrictions on the placement of lock and unlock steps in a transaction in order to increase the potential number of transactions that can concurrently access a database. These additional restrictions are defined for both the two-phase locking and the tree-locking protocols.;Additionally, in another approach to increasing the potential number of transactions that can concurrently access a database, we define a new version of the tree-locking protocol. This new version of the tree-locking protocol allows multiple data access trees to be defined over a database. These data access trees are defined at the time of transaction execution.