Species distribution data play an important role in biodiversity related research, especially in exploring relationships with the environment. In the recent years, both the number of species being explored and the spatial resolution of species distribution data are increasing fast. It is thus imperative to develop database systems that allow users to efficiently query such large-scale data based on spatial and non-spatial (e.g., taxonomic and phylogenetics) criteria.
In this paper, we present our approach to building such a system by integrating several components, including a quadtree representation of binary raster data, tree path indexing and query processing in PostgreSQL, and window decomposition techniques for spatial queries. Our unique contribution is in associating species identifiers with intermediate quadtree nodes and query optimization for multiple independent queries after window query decomposition. Our system enables PostgreSQL to support binary raster data without requiring any changes to the database backend and is suitable for managing large-scale species distribution data.
Our experiments using 4000+ bird species distribution data related to the Western hemisphere show that the proposed approach in associating species identifiers with quadtree nodes reduces the number of database tuples by more than 1/3 and the average identifiers to be associated with each tuple from 110.6 to 4.8, a significant improvement compared to classic quadtree-based approaches. With respect to query optimization, optimized queries are 6--9.5 times faster than the baseline queries for average query response times and 5.5--8.3 times faster than the baseline queries for maximum query response times for four query window sizes ranging from 0.1 to 5.0 degrees. Our query optimization techniques thus make the system suitable for many interactive applications for querying and exploring species distribution data.
Jianting Zhang, Michael Gertz, Le Gruenwald,
Large-Scale Raster Species Distribution Data in PostgreSQL.
ACM-GIS09, Nov. 4-6,