The impact of spatial data redundancy on SOLAP query performance

Abstract

Geographic Data Warehouses (GDW) are one of the main technologies used in decision-making processes and spatial analysis, and the literature proposes several conceptual and logical data models for GDW. However, little effort has been focused on studying how spatial data redundancy affects SOLAP (Spatial On-Line Analytical Processing) query performance over GDW. In this paper, we investigate this issue. Firstly, we compare redundant and non-redundant GDW schemas and conclude that redundancy is related to high performance losses. We also analyze the issue of indexing, aiming at improving SOLAP query performance on a redundant GDW. Comparisons of the SB-index approach, the star-join aided by R-tree and the star-join aided by GiST indicate that the SB-index significantly improves the elapsed time in query processing from 25% up to 99% with regard to SOLAP queries defined over the spatial predicates of intersection, enclosure and containment and applied to roll-up and drill-down operations. We also investigate the impact of the increase in data volume on the performance. The increase did not impair the performance of the SB-index, which highly improved the elapsed time in query processing. Performance tests also show that the SB-index is far more compact than the star-join, requiring only a small fraction of at most 0.20% of the volume. Moreover, we propose a specific enhancement of the SB-index to deal with spatial data redundancy. This enhancement improved performance from 80 to 91% for redundant GDW schemas.

Benchmarking Spatial Data Warehouses

“…We validated the Spadawan benchmark using it to generate a performance evaluation environment to assess the impact of spatial data redundancy over SOLAP queries [6] and the efficiency of the SB-index data structure [16]. As future work, we intend to propose additional SOLAP query types to analyze drill-across operations on extended SDW schemas and to compute aggregations of geometries of spatial objects.…”

“…We have already used the Spadawan benchmark to investigate the impact of spatial data redundancy over SDW [6]. We loaded the following datasets: D1: the redundant schema using the scale factor S = 10, which occupied 150 GB; D2: the hybrid schema with S = 10, which occupied 15 GB; D3: the hybrid schema with S = 6; and D4: the hybrid schema with S = 2.…”

BMF: Bitmapped Mass Fingerprinting for Fast Protein Identification

“…FastBit is an open source tool, and is used by many applications without any involvement of the FastBit developers. For example, Yahoo employs FastBit to query internal data about advertisements, a German bioinformatics company utilizes it to speedup molecular docking [17], and a Brazilian research group uses it in a geographical data warehousing system [18].…”

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

“…Embora existam diversos métodos na literatura que visem melhorar o desempenho de consultas em DWs e DWGs, tais como visão materializada (Agrawal et al, 2000;Baikousi e Vassiliadis, 2009;Hung et al, 2007;Kotidis e Roussopoulos, 2001), fragmentação horizontal e vertical de dados (Bellatreche e Woameno, 2009;Ciferri et al, 2007;Golfarelli et al, 2004b), particionamento dos dados para processamento paralelo (Benkrid et al, 2008;Costa e Madeira, 2004) e índices (Johnson e Shasha, 1997;Papadias et al, 2001Papadias et al, , 2002Sarawagi, 1997;Siqueira et al, 2009bSiqueira et al, , 2008Siqueira et al, , 2009a, não existem na literatura trabalhos voltados ao processamento de consultas SOLAP drill-across e consultas SOLAP com junção espacial. Surge, então, a necessidade de se propor métodos de processamento que enfoquem essas consultas SOLAP complexas.…”

“…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.…”