DATABASE STRUCTURES

摘要

A hierarchical index structure, for a multi-dimensional information database, is such that at least one index entry partition (d) may be disposed at a higher index tree level than the hierarchical level to which it corresponds. This change of level (promotion) occurs when a data distribution changes or the pattern of insertions/deletions is very skewed to particular areas of the dataspace. Whilst this makes the index tree unbalanced, it facilitates the addition of information to and the searching of such a database.