A method for processing data received at a node in a network, the method including: receiving records from one or more sources in the network, at least some of the records each being associated with an identifier; for each of multiple intervals of time, attempting a matching procedure on sets of one or more records, the matching procedure including comparing identifiers associated with different records to generate the sets and determining whether or not a completeness criterion is satisfied for one or more of the sets, where the completeness criterion for a particular set of one or more records is based at least in part on a result of aggregating at least some records in that particular set; for at least some of the intervals of time, processing at least one complete set of records, for which the completeness criterion was satisfied during that attempt, consisting of one or more of the received records on which the matching procedure is first attempted during the interval of time and one or more records stored in a data store before the interval of time; for at least some of the intervals of time, processing at least one incomplete set of records, for which the completeness criterion was not satisfied during that attempt, consisting of one or more records stored in the data store before the interval of time, wherein an incomplete set of records is processed after at least two attempts of the matching procedure in response to comparison of a time associated with at least one record in the incomplete set of records with an expiration criterion, and wherein the expiration criterion depends on a degree of incompleteness of the incomplete set of records; after at least some attempts of the matching procedure, storing in the data store at least some incomplete sets of records for which the completeness criterion was not satisfied during that attempt, and storing keys corresponding to the incomplete sets of records in a data structure separate from the data store; and retrieving stored keys from the data structure to attempt the matching procedure on corresponding records during a subsequent interval of time. receiving records from one or more sources in the network, at least some of the records each being associated with an identifier; for each of multiple intervals of time, attempting a matching procedure on sets of one or more records, the matching procedure including comparing identifiers associated with different records to generate the sets and determining whether or not a completeness criterion is satisfied for one or more of the sets, where the completeness criterion for a particular set of one or more records is based at least in part on a result of aggregating at least some records in that particular set; for at least some of the intervals of time, processing at least one complete set of records, for which the completeness criterion was satisfied during that attempt, consisting of one or more of the received records on which the matching procedure is first attempted during the interval of time and one or more records stored in a data store before the interval of time; for at least some of the intervals of time, processing at least one incomplete set of records, for which the completeness criterion was not satisfied during that attempt, consisting of one or more records stored in the data store before the interval of time, wherein an incomplete set of records is processed after at least two attempts of the matching procedure in response to comparison of a time associated with at least one record in the incomplete set of records with an expiration criterion, and wherein the expiration criterion depends on a degree of incompleteness of the incomplete set of records; after at least some attempts of the matching procedure, storing in the data store at least some incomplete sets of records for which the completeness criterion was not satisfied during that attempt, and storing keys corresponding to the incomplete sets of records in a data structure separate from the data store; and retrieving stored keys from the data structure to attempt the matching procedure on corresponding records during a subsequent interval of time.