Detecting redundant materialized views in data warehouse evolution

Theodoratos, D

dc.contributor.author	Theodoratos, D	en
dc.date.accessioned	2014-03-01T01:16:23Z
dc.date.available	2014-03-01T01:16:23Z
dc.date.issued	2001	en
dc.identifier.issn	0306-4379	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14020
dc.subject	Data warehouse evolution	en
dc.subject	Materialized views	en
dc.subject	Redundant views	en
dc.subject	View maintenance	en
dc.subject	View usability	en
dc.subject.classification	Computer Science, Information Systems	en
dc.subject.other	Decision support systems	en
dc.subject.other	Evolutionary algorithms	en
dc.subject.other	Mathematical models	en
dc.subject.other	Query languages	en
dc.subject.other	Redundancy	en
dc.subject.other	Data warehouse evolution	en
dc.subject.other	Materialized views	en
dc.subject.other	Redundant views	en
dc.subject.other	View maintenance	en
dc.subject.other	View usability	en
dc.subject.other	Data warehouses	en
dc.title	Detecting redundant materialized views in data warehouse evolution	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0306-4379(01)00025-4	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0306-4379(01)00025-4	en
heal.language	English	en
heal.publicationDate	2001	en
heal.abstract	A data warehouse (DW) can be abstractly seen as a set of materialized views defined over a set of remote data sources. A DW is intended to satisfy a set of queries. The views materialized in a DW relate to each other in a complex manner, through common subexpressions, in order to guarantee high query performance and low view maintenance cost. DWs are time varying. As time passes new materialized views are added in order to satisfy new queries, or for performance reasons, while old queries are dropped. The evolution of a DW can result in a redundant set of materialized views. In this paper, we address the problem of detecting redundant materialized views in a given DW view selection, that is, materialized views that can be removed from DW without negatively affecting the query evaluation or the view maintenance process. Using an AND/OR dag representation for multiple queries and views, we first formalize the process of propagating source relation changes to the materialized views by exploiting common subexpressions between views and by using other materialized views that are not affected by these changes. Then, we provide an algorithm for detecting materialized views that are not needed in the process of propagating source relation changes to the DW. We also show how trivially redundant views can be identified in this process. Finally, we use these results to provide a procedure for detecting materialized views that are redundant in a DW. Our approach considers a broad class of views that includes grouping/aggregation views and is not dependent on a specific cost model. (C) 2001 Elsevier Science Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Information Systems	en
dc.identifier.doi	10.1016/S0306-4379(01)00025-4	en
dc.identifier.isi	ISI:000170418300003	en
dc.identifier.volume	26	en
dc.identifier.issue	5	en
dc.identifier.spage	363	en
dc.identifier.epage	381	en