Data/hora: 08/06/2024 00:33:51

Biblioteca(s): 	Embrapa Agricultura Digital.	
Data corrente: 	23/09/2010	
Data da última atualização: 	18/10/2010	
Autoria: 	AZEVEDO, L. G.; ZIMBRÃO, G.; SOUZA, J. M. de.	
Afiliação: 	LEONARDO GUERREIRO AZEVEDO, URFJ; GERALDO ZIMBRÃO, UFRJ; JANO MOREIRA DE SOUZA, UFRJ.	
Título: 	Approximate query processing in spatial databases using raster signatures.	
Ano de publicação: 	2007	
Fonte/Imprenta: 	In: DAVID JUNIOR, C. A.; MONTEIRO, A. M. V. (Ed.). Advances in Geoinformatics. Berlin: Springer-Verlag, 2007.	
Páginas: 	p. 69-86.	
Idioma: 	Inglês	
Conteúdo: 	This work is concerned with the use of raster signatures in approximate query processing in spatial databases. We extended the proposals of Azevedo et al. (2004, 2005) of using Four-Color Raster Signature (4CRS) (Zimbrao and Souza, 1998) for fast and approximate processing of queries over polygon datasets. We propose several new algorithms for a set of spatial operations that can be processed approximately using 4CRS. 4CRS stores the main data characteristics in an approximate and compact representation that can be accessed and processed faster than real data. By doing so, the exact geometries of objects are not processed during query execution, which is the most costly step of a spatial operation, since it requires to search and to transfer large objects from disk to main storage (Brinkhoff et al., 1994; Lo and Ravishankar, 1996). Also, the exact processing needs to use CPU-time intensive algorithms to decide whether the objects match the query condition (Brinkhoff et al., 1993). As a result, the approximate query answer is returned in a shorter time than the time to return an exact answer. On the other hand, the answer is estimated and not exact, so a precision measure is also returned as a confidence interval that allows the user to decide if the accuracy of the response is sufficient. In general, this approximate answer is enough for many applications.	
Palavras-Chave: 	Database management systems; Query processing in spatial databases; Raster signatures.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Agricultura Digital (CNPTIA)	
Exemplares: 	CNPTIA - (14983-1) - ADD - PL - PP - 526 - BRA - 2010.00008 - DIS