13. A method for matching objects using keys based on match rules, the method comprising: generating a match rule key based on a match rule, wherein the match rule specifies whether two objects match; creating a plurality of candidate keys by applying the match rule key to a plurality of data objects; creating a probe key by applying the match rule key to a probe object; determining whether the probe key matches a candidate key of the plurality of candidate keys; determining whether the probe object matches a candidate object based on applying the match rule to the probe object and the candidate object in response to a determination that the probe key matches the candidate key corresponding to the candidate object; and identifying the probe object and the candidate object as matching based on the match rule in response to a determination that the probe object matches the candidate object, the match rule identifying a match of the probe object and the candidate object unless both the probe object and the candidate object have corresponding non-empty fields that lack a match.
13. A method for matching objects using keys based on match rules, the method comprising: generating a match rule key based on a match rule, wherein the match rule specifies whether two objects match; creating a plurality of candidate keys by applying the match rule key to a plurality of data objects; creating a probe key by applying the match rule key to a probe object; determining whether the probe key matches a candidate key of the plurality of candidate keys; determining whether the probe object matches a candidate object based on applying the match rule to the probe object and the candidate object in response to a determination that the probe key matches the candidate key corresponding to the candidate object; and identifying the probe object and the candidate object as matching based on the match rule in response to a determination that the probe object matches the candidate object, the match rule identifying a match of the probe object and the candidate object unless both the probe object and the candidate object have corresponding non-empty fields that lack a match. 14. The method of claim 13 , wherein the match rule is expressed in disjunctive normal form.