Domain based partitioning and reclustering of relations in object- oriented relational database management systems

摘要

A system and method of logically and physically clustering data (tuples) in a database. The database management system of the invention partitions (declusters) a set of relations into smaller so- called local relations and reclusters the local relations into constructs called domains. The domains are self-contained in that a domain contains the information for properly accessing and otherwise manipulating the data it contains. In other words, the data objects stored in the domains may be stored in a particular domain based upon a locality-of-reference algorithm in which a tuple of data is placed in a domain if and only if all objects referenced by the tuple are contained in the domain. On the other hand, the data objects stored in a domain may be clustered so that a tuple of data is placed in a domain based on the domain of the object referenced by a particular element of the tuple. By clustering the related object data in this manner, the database management system may more efficiently cache data to a user application program requesting data related to a particular data object. The system may also more efficiently lock and check-in and check-out data from the database so as to improve concurrency. Moreover, versioning may be more readily supported by copying tuples of a particular domain into a new domain which can then be updated as desired.