Summary catalogs.

摘要

A system provides support for the use of summary catalog data structures. In particular, the system defines such summary catalogs as data structures and provides standardized methods for operating on the data structures. The summary catalogs provide a convenient and highly available mechanism for obtaining information regarding files in the system. The summary catalogs are closely tied to queries in that the summary catalogs store query results. The summary catalogs may be encapsulated into objects that hold selected properties that are derived from other objects in a query or may be formed by other mechanisms. Copies of a summary catalog may be kept consistent using replication that propagates changes. In addition, consistency of summary catalogs with the source objects from which they originated may be maintained.