Abstract: Data is stored persistently. At least two different items of the data are stored in two different non-conflicting regions or two different physical clusters. A relationship is maintained between the two different items of data. The relationship enables a process to reach any one of the data items from the other data item. Consistency of the relationship is maintained notwithstanding updates of either or both of the items.

Abstract: Among other things, a user is enabled to identify arbitrary data records of interest that belong to a file of data records that are expressed in an arbitrary format. Pre-generated information about the records of the file is used to enable a user to view a portion of the arbitrary data records that a machine is capable of displaying at one time. The amount of time required to enable the user to view the portion after the data records of interest have been identified is essentially independent of the number of records in the file. The file and the pre-generated information about the records of the file are each too large to be stored, as a whole, in a memory that is used by the machine in accessing the arbitrary data records in response to the user's identification of records of interest.