Summary: CRB­Tree: An Efficient Indexing Scheme for
Range­Aggregate Queries ?
Sathish Govindarajan, Pankaj K. Agarwal, and Lars Arge
Department of Computer Science, Duke University, Durham, NC 27708
fgsat, pankaj, largeg@cs.duke.edu
Abstract. We propose a new indexing scheme, called the CRB­tree, for effi­
ciently answering range­aggregate queries. The range­aggregate problem is de­
fined as follows: Given a set of weighted points in R d , compute the aggregate of
weights of points that lie inside a d­dimensional query rectangle. In this paper
we focus on range­COUNT, SUM, AVG aggregates. First, we develop an indexing
scheme for answering two­dimensional range­COUNT queries that uses O(N=B)
disk blocks and answers a query in O(log B N) I/Os, where N is the number of
input points and B is the disk block size. This is the first optimal index struc­
ture for the 2D range­COUNT problem. The index can be extended to obtain a
near­linear­size structure for answering range­SUM queries using O(log B N)
I/Os. We also obtain similar bounds for rectangle­intersection aggregate queries,
in which the input is a set of weighted rectangles and a query asks to compute
the aggregate of the weights of those input rectangles that overlap with the query
rectangle. This result immediately improves a recent result on temporal­aggregate
queries. Our indexing scheme can be dynamized and extended to higher dimen­

Source: Arge, Lars - Department of Computer Science, Aarhus Universitet

Collections: Computer Technologies and Information Sciences