The SB-index and the HSB-index: efficient indices for spatial data warehouses

Abstract

Spatial data warehouses (SDWs) allow for spatial analysis together with analytical multidimensional queries over huge volumes of data. The challenge is to retrieve data related to ad hoc spatial query windows according to spatial predicates, avoiding the high cost of joining large tables. Therefore, mechanisms to provide efficient query processing over SDWs are essential. In this paper, we propose two efficient indices for SDW: the SB-index and the HSB-index. The proposed indices share the following characteristics. They enable multidimensional queries with spatial predicate for SDW and also support predefined spatial hierarchies. Furthermore, they compute the spatial predicate and transform it into a conventional one, which can be evaluated together with other conventional predicates by accessing a star-join Bitmap index. While the SB-index has a sequential data structure, the HSB-index uses a hierarchical data structure to enable spatial Geoinformatica (2012) 16:165-205 objects clustering and a specialized buffer-pool to decrease the number of disk accesses. The advantages of the SB-index and the HSB-index over the DBMS resources for SDW indexing (i.e. star-join computation and materialized views) were investigated through performance tests, which issued roll-up operations extended with containment and intersection range queries. The performance results showed that improvements ranged from 68% up to 99% over both the star-join computation and the materialized view. Furthermore, the proposed indices proved to be very compact, adding only less than 1% to the storage requirements. Therefore, both the SB-index and the HSB-index are excellent choices for SDW indexing. Choosing between the SB-index and the HSBindex mainly depends on the query selectivity of spatial predicates. While low query selectivity benefits the HSB-index, the SB-index provides better performance for higher query selectivity.

Conceptual design and implementation of spatial data warehouses integrating regular grids of points

“…As described in (Bimonte, 2010), the first tier of a classical relation SOLAP architecture is responsible for managing the storage of spatial data using relational Spatial DBMS with some extensions of the star and snowflake schemas. For example, (Siqueira et al, 2012) denormalizes only the geometrical attributes of the classical star schema to improve the computation performance.…”

A Hierarchical Tensor-Based Approach to Compressing, Updating and Querying Geospatial Data

“…Multidimensional data are stored and accessed linearly in memory and on hard disk but should be randomly queried and updated from any dimension. Classical methods use data indexes (e.g., Pyramid, RTree, VA-Files) to accelerate the query and storage [4]. These data indexes split data into segments and then map the segments to the linear ordered data I/O sequence [5].…”

Processamento de consultas SOLAP drill-across e com junção espacial em data warehouses geográficos

“…4.10 Estrutura do HSB-index -extraída de (Siqueira et al, 2012 Um data warehouse (DW) é um banco de dados especialmente organizado para armazenar dados orientados a assunto, integrados, históricos e não-voláteis. Além disso, ele é multidimensional, ou seja, um DW possui um conjunto de medidas numéricas, que são os objetos de análise relevantes ao negócio, e um conjunto de dimensões, as quais determinam o contexto para as medidas numéricas.…”

“…Outro trabalho correlato, o qual envolve junção espacial em DWGs, consiste na proposta dos índices SJELI e SJALI (Mohan et al, 2008) (seção 4.3). As propostas dos índices SB-index (Siqueira et al, 2009b(Siqueira et al, , 2008(Siqueira et al, , 2009a e HSB-index (Siqueira et al, 2012) são descritas nas seções 4.4 e 4.5, respectivamente. Em especial, o SB-index é um índice precursor ao trabalho desenvolvido nesta dissertação, ou seja, ele é usado como base para a proposta das estratégias de processamento de consultas SOLAP drill-across e com junção espacial.…”

“…O Hierarchical Spatial Bitmap Index (HSB-index) (Siqueira et al, 2012) é uma variação do SB-index. Nessa nova proposta, a estrutura sequencial do índice espacial foi substituída por uma estrutura na forma hierárquica (como exemplo, a R*-Tree).…”