Method of extracting item patterns across a plurality of databases, a network system and a processing apparatus

摘要

The invention relates to an item pattern straddling over two or more databases with different structure and/or attributes is extracted from the databases based on a comparison of partial data. The support count for the item pattern is counted by communicating a list of identifiers for records, the number of the identifiers, or a subset of the item pattern between the databases. For an item pattern with a known support count, an upper-bound value of the support counts for subsets of that item pattern is calculated on the basis of a difference in the support counts for the subsets, thereby limiting the item patterns for which the support counts are to be counted.