Valid-Time Indexing

DEFINITION A valid-time index is a temporal index that enables fast access to valid-time datasets. In a traditional database, an index is used for selection queries. When accessing valid-time databases such selections also involve the valid-time dimension (the time when a fact becomes valid in reality). The characteristics of the valid-time dimension imply various properties that the temporal index should have in order to be efficient. As traditional indices, the performance of a temporal index is described by three costs: (i) storage cost (i.e., the number of pages the index occupies on the disk), (ii) update cost (the number of pages accessed to perform an update on the index; for example when adding, deleting or updating a record), and (iii) query cost (the number of pages accessed for the index to answer a query).