The delay due to dynamic two-phase locking

An analytic formula for the delay due to two-phase locking is developed in terms of mean values for the input parameters using an open queuing network model in equilibrium. The results of simulations, using various realistic probability distributions governing the number of locks that transactions request, are presented to validate the formula. Reasonably good accuracy is achieved for gamma distributions over a wide range of parameter settings. The simulations also provided evidence that the rate of deadlock, often disregarded in the literature, can be high in certain heavily utilized databases.<
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