We address the problem of executing high level language queries submitted to a relational data base system. As a step in the process of constructing an “efficient” compiler for a high level language we suggest the elaboration of an intermediate level language acting as a target language for the optimizer part of the compiler. This language may be conceived as one of several levels in a chain of abstract machines mapping a nonprocedural relational language onto primitive data base access operations. It is our conjecture that the introduction of an access specification language provides a conceptual platform facilitating the handling of the “optimization” problem.
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