The disclosed embodiments provide a system for processing data. During operation, the system obtains a set of records from a set of inputs, with each record containing an entity key, a partition key, and one or more attribute-value pairs. Next, the system sorts and indexes the records by the entity key for each partitioned input. The system then processes a query of the records by matching entity key values to the sorted and indexed records for each input partition in the query. Next, the system merges the subset of records with the same entity key values into records, with each merged record containing an entity key field and a single field that includes a list of attribute-value pairs from the subset. Finally, the system outputs the merged records in response to the query.