An automated blocking technique is used as a first step to find
approximate matches in a database. The technique builds a blocking set to
be as liberal as possible in retrieving records that match on individual
fields or sets of fields while avoiding selection criteria that are
predicted to return more than the maximum number of records defining a
particular special requirement. The ability to do blocking without
extensive manual setup at low cost is highly advantageous especially when
using a machine learning based second-stage matching algorithm.