Projection of the memory size necessary for implementation of supertype-subtype relations

In real databases the considerable part of the data is connected by supertype-subtype relations.To reduce the memory resources the technique considered in the paper can be used by designingof structures of databasesThere is proposed a method of modeling of structures of the databases with supertype-typerelations. In model are taken into account the memory size for data storage of different subtypesand a ratio of the sizes of attributes of different subtypes. For evaluation of required memory sizethe analytical expressions are obtained. The diagrams of dependences of memory size on modelparameters of a database and on a variant of implementation of supertype-subtype relations aregiven. The simulation modeling program is applied to specification of parameters in analyticalexpressions. By making use of this program the coefficients of data compression in a DBMS andexpenses of storage are found.Obtained estimations can be applied to choosing a variant of implementation of supertypesubtyperelations in databases.

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