19. A system to halt execution of queries containing entity resolution (ER) candidate-building keys unsuitable for generating a restricted set of candidate entities against which to match a received identity record, the system comprising: one or more computer processors; a memory containing a program which, when executed by the one or more computer processors, is configured to perform an operation comprising: receiving an identity record; determining a plurality of ER candidate-building keys for the received identity record; generating a query from one or more of the plurality of ER candidate-building keys to retrieve entities matching any of the one or more ER candidate-building keys, wherein the one or more ER candidate-building keys are derived from at least a field of the received identity record; and upon determining, during execution of the query, that at least a first ER candidate-building key of the one or more ER candidate-building keys is unsuitable for generating a restricted set of candidate entities against which to match the received identity record, aborting executing the query, wherein the restricted set of candidate entities is selected from a plurality of available entities greater in number than the restricted set of candidate entities.
24. The system of claim 19 , wherein the executing of the query is aborted upon further identifying another unsuitable ER candidate-building key from the one or more ER candidate-building keys.