TY - GEN
T1 - Detecting redundancy in data warehouse evolution
AU - Theodoratos, Dimitri
N1 - Publisher Copyright:
© Springer-Verlag Berlin Heidelberg 1999.
PY - 1999
Y1 - 1999
N2 - 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 sub expressions, 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 views in a given DW view selection, that is, views that can be removed from the 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 provide a method for detecting materialized views that are not needed in the process of propagating source relation changes to the DW. Then, we use this method to detect materialized views that are redundant. As a side effect, our approach shows how source relation changes can be propagated to the DW materialized views by exploiting common sub expressions between views and by using other materialized views that are not affected by these changes.
AB - 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 sub expressions, 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 views in a given DW view selection, that is, views that can be removed from the 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 provide a method for detecting materialized views that are not needed in the process of propagating source relation changes to the DW. Then, we use this method to detect materialized views that are redundant. As a side effect, our approach shows how source relation changes can be propagated to the DW materialized views by exploiting common sub expressions between views and by using other materialized views that are not affected by these changes.
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U2 - 10.1007/3-540-47866-3_23
DO - 10.1007/3-540-47866-3_23
M3 - Conference contribution
AN - SCOPUS:84947941656
SN - 3540666869
SN - 9783540666868
T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
SP - 340
EP - 355
BT - Conceptual Modeling – ER 1999 - 18th International Conference on Conceptual Modeling, Proceedings
A2 - Akoka, Jacky
A2 - Bouzeghoub, Mokrane
A2 - Metais, Elisabeth
A2 - Comyn-Wattiau, Isabelle
PB - Springer Verlag
T2 - 18th International Conference on Conceptual Modeling, ER 1999
Y2 - 15 November 1999 through 18 November 1999
ER -