Patent ID: 7324988

Claim:
A method for parallel query processing, the method comprising the steps of: providing a set of node indices for text indexing a set of documents, each node text index covering a subset of the documents, each term of the node indices having an assigned precalculated global frequency measure, the global frequency measure being expressive of a frequency of documents containing the term in the set of documents and each node text index having an assigned precalculated quality measure, the quality measure being expressive of a difference between the global frequency measure of a term and the local frequency measure of the term within the subset of documents covered by the node ( 102 , 104 , 106 , 108 ); determining if a quality of the distributed text index is sufficient on the basis of the quality measure of the node indices by performing the steps of: for each node text index: calculation of a difference of the quality measure and the precalculated quality measure; calculating a mean value of the differences; if the mean value of the differences is above a user-defined threshold level, recalculation of the global frequency measures; using of the precalculated global frequency measures for calculating of rank scores, if the quality is sufficient; and recalculating of the global frequency measures and of the quality measure of the nodes, if the quality is not sufficient; and calculating of rank scores on the basis of the global frequency measures.