APPARATUS AND METHOD FOR AGGREGATE INDEXES

An aggregate index is used for accessing an aggregate value associated with one or more rows of a database table. The aggregate values are stored in the index entries of the index, thus allowing determination of aggregate values without accessing the underlying database table. The aggregate index is created by determining an aggregate value associated with an index entry, and storing the aggregate value with the index entry. The aggregate value is determined by accessing information corresponding to the index entry and processing the information. In the case of an index entry in the form of a branch node, the information might be aggregate values from other nodes, or values of items in the database pointed to by the index entries that are leaf nodes. The aggregate values may be stored in index entries of any type of index.