Multi‐Resolution Aggregate Tree

Synonyms

MRA-Tree; Ra*-Tree; aR-Tree

Definition

A Multi‐resolution Aggregate tree (MRA-tree) is a multi‐dimensional indexing structure whose nodes are augmented with aggregate information about the indexed subsets of data. Typically, such indices subdivide space or group data objects; nodes contain routing information for their children nodes, e. g., in the form of spatial partitions (as in quad-trees) or bounding rectangles (as in R-trees). MRA-trees store, in addition to this information, aggregate properties of the indexed entities, e. g., the SUM of their values, the MIN value, etc. Several such aggregates can be stored or alternatively, only those that are often queried.

Main Text

MRA-trees are useful in answering aggregate queries approximately and in a progressive manner. Traditional multi‐dimensional indexes help aggregate query answering by quickly gathering all relevant tuples. However, they have the limitation that each of those tuples must be handled individually. Moreover,...