Abstract: A computer data storage management system includes a memory employing a hierarchical data structure comprising a plurality of nodes (root, branch and leaf), in particular a multi-dimensional information database. The branch nodes are index nodes and the leaf nodes are data nodes. The index nodes are arranged in an index tree structure. When extra information inserted into the memory results in index node overflow, the index node is split and, in certain specified circumstances, an index entry will become disposed at an index tree level higher than the hierarchical level to which it corresponds, i.e. is promoted. Whilst this makes the index tree unbalanced, it facilitates the addition of information to and the searching of such a database.