The ATree: A data structure to support very large scientific databases

Abstract

The datasets generated by satellite observations and super- computer simulations are overwhelming conventional methods of storage and access, leading to unreasonably long delays in data analysis. The major problem that we address is the slow access, from large datasets in archival storage, to small subsets needed for scientific visualization and analysis. The goal is to minimize the amount of storage that has to be read when a subset of the data is needed. A second goal is to enhance the accessibility of data subsets by applying data reduction and indexing methods to the subsets. The reduced format allows larger datasets to be stored on local disk for analysis. Data indexing permits efficient manipu-lation of the data, and thus improves the productivity of the researcher. A data structure called the ATree is described that meets the demands of interactive scientific applications. The ATree data structure is suit- able for storing data abstracts as well as original data. It allows quick access to a subset of interest and is suitable for feature-based queries. It intrinsically partitions the data and organizes the chunks in a lin- ear sequence on secondary/tertiary storage. It can store data at various resolutions and incorporates hierarchical compression methods.