Establishing arc consistency for multiple database views
This paper introduces a class of problems where it is desirable to develop a number of potential search orders in advance. These problems emerge from a database environment in which the high volume of transactions means that pre-processing of the data can make a big difference to run-time performance. Furthermore, the kinds of queries that are made to this database are fairly stereotypical and are derived from a finite set of views of the database. The access path for each view may be expressed as a set of total variable orderings. Seen as a single partial ordering the question then arises as to how local consistency is to be established. Rather than enforcing consistency for each view separately the partial order is processed as a single structure. By organising the variables into groups of mutually dependent variables, this high level structure may be processed in a single DAC-like pass, while full arc-consistency is obtained for each sub-group.
KeywordsDirected Graph Boolean Network Input Combination Constraint Graph Local Consistency
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