Importance

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Abstract

A priority scheme is used to control concurrent access to a database. The priority scheme takes advantage of the usual delay in a process after a first full set of data is accessed in order to improve the overall impression of the speed of the system. Access to the database is granted on the basis of priority. In the disclosed exemplary embodiment of the invent ion, three priorities are established: a first priority for fast-response type transactions which have not yet accessed a set of data, a second priority for fast-response transactions which have accessed a set of data, and a third priority for batch transactions. When a fast-response transaction is initiated, it is given the first priority. Once a predefined number of data values have been obtained from the database, enough to produce a full screen display, the transaction receives the second priority. A transaction may be assigned the first priority periodically, when it needs to access a further set of data. A first priority transaction can block a second priority transaction and can kill a third priority transaction. A first priority transaction can only block a second priority transaction. A second priority transaction is not necessarily given priority over a third priority transaction, however.

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First Claim