Clustering-Based Materialized View Selection in Data Warehouses

Materialized view selection is a non-trivial task. Hence, its complexity must be reduced. A judicious choice of views must be cost-driven and influenced by the workload experienced by the system. In this paper, we propose a framework for materialized view selection that exploits a data mining technique (clustering), in order to determine clusters of similar queries. We also propose a view merging algorithm that builds a set of candidate views, as well as a greedy process for selecting a set of views to materialize. This selection is based on cost models that evaluate the cost of accessing data using views and the cost of storing these views. To validate our strategy, we executed a workload of decision-support queries on a test data warehouse, with and without using our strategy. Our experimental results demonstrate its efficiency, even when storage space is limited

A solution to the materialized view selection problem in data warehousing

One of the most important decisions in the physical designing of a data warehouse is the selection of materialized views and indexes to be created. The problem is to select an appropriate set of views and indexes to storage that minimizes the total query response time, as long as the cost of maintaining them, given a constraint of some resource like storage space, is kept as low as possible.In this work, we have developed a new algorithm for the general problem of se-lection of views considering indexes, as an extension to a well-known algorithm. We present a heuristic for selection of views and indexes to optimize total que-ry response under a materialization time constraint. Finally, we present an ex-perimental comparison of our proposal with the considered state-of-art ap-proach.XI Workshop Bases de Datos y Minería de DatosRed de Universidades con Carreras de Informática (RedUNCI

A solution to the materialized view selection problem in data warehousing

One of the most important decisions in the physical designing of a data warehouse is the selection of materialized views and indexes to be created. The problem is to select an appropriate set of views and indexes to storage that minimizes the total query response time, as long as the cost of maintaining them, given a constraint of some resource like storage space, is kept as low as possible.In this work, we have developed a new algorithm for the general problem of se-lection of views considering indexes, as an extension to a well-known algorithm. We present a heuristic for selection of views and indexes to optimize total que-ry response under a materialization time constraint. Finally, we present an ex-perimental comparison of our proposal with the considered state-of-art ap-proach.XI Workshop Bases de Datos y Minería de DatosRed de Universidades con Carreras de Informática (RedUNCI

Greedy Selection of Materialized Views

Greedy based approach for view selection at each step selects a beneficial view that fits within the space available for view materialization. Most of these approaches are focused around the HRU algorithm, which uses a multidimensional lattice framework to determine a good set of views to materialize. The HRU algorithm exhibits high run time complexity as the number of possible views is exponential with respect to the number of dimensions. The PGA algorithm provides a scalable solution to this problem by selecting views for materialization in polynomial time relative to the number of dimensions. This paper compares the HRU and the PGA algorithm. It was experimentally deduced that the PGA algorithm, in comparison with the HRU algorithm, achieves an improved execution time with lowered memory and CPU usages. The HRU algorithm has an edge over the PGA algorithm on the quality of the views selected for materialization

Avaliação de algoritmos para a selecção de vistas materializadas em ambientes de data warehousing

A competição no mundo empresarial obriga a uma monitorização mais apertada de todas as variáveis envolvidas nas actividades de negócio. Com o objectivo de suportar o processo de tomada de decisão em factos, e não apenas na intui-ção dos agentes de decisão, surgiram os sistemas de suporte à decisão. Estes sistemas são hoje uma ferramenta chave no processo de tomada de decisão, pois conciliam e integram toda a informação disponível numa única plataforma tec-nológica. Assim, todas as técnicas de optimização do desempenho desses siste-mas são bem-vindas. De entre as diversas técnicas disponíveis, este trabalho concentra-se na materialização de vistas como método de optimização do pro-cessamento de interrogações. A materialização de vistas consiste na antecipação do processamento e armazenamento dos tuplos resultantes do processamento da sua definição numa tabela. De facto, o tempo de reposta a uma interrogação é menor, se as operações intermédias como selecções, projecções, junções e a-gregações se encontrarem já armazenadas numa tabela. Desta forma, o tempo de resposta limita-se ao varrimento da vista materializada. Este artigo apresenta um estudo preliminar para o desenvolvimento de um sistema de gestão de vistas materializadas em ambientes de data warehousing. Neste trabalho comparam-se, basicamente, os comportamentos de dois algoritmos de selecção de vistas materializadas: o BPUS e o A*, ambos algoritmos de procura exaustiva (deter-minísticos)

XML Reconstruction View Selection in XML Databases: Complexity Analysis and Approximation Scheme

Query evaluation in an XML database requires reconstructing XML subtrees rooted at nodes found by an XML query. Since XML subtree reconstruction can be expensive, one approach to improve query response time is to use reconstruction views - materialized XML subtrees of an XML document, whose nodes are frequently accessed by XML queries. For this approach to be efficient, the principal requirement is a framework for view selection. In this work, we are the first to formalize and study the problem of XML reconstruction view selection. The input is a tree $T$, in which every node $i$ has a size $c_i$ and profit $p_i$, and the size limitation $C$. The target is to find a subset of subtrees rooted at nodes $i_1,\cdots, i_k$ respectively such that $c_{i_1}+\cdots +c_{i_k}\le C$, and $p_{i_1}+\cdots +p_{i_k}$ is maximal. Furthermore, there is no overlap between any two subtrees selected in the solution. We prove that this problem is NP-hard and present a fully polynomial-time approximation scheme (FPTAS) as a solution

Optimized Generation and Maintenance of Materialized View using Adaptive Mechanism

Data Warehouse is storage of enormous amount of data gathered from multiple data sources, which is mainly used by managers for analysis purpose. Hence to make this data available in less amount of time is essential. Using Materialize view we can have result of query in less amount of time compared to access the same from base tables. To materialize all of the views is not possible since it requires storage space and maintenance cost. So it is required to select materialized view which minimizes response time of query and cost of maintenance. In this paper, effective approach is suggested for selection and maintenance of materialize view. DOI: 10.17762/ijritcc2321-8169.15050

EFFICIENT APPROACH FOR VIEW SELECTION FOR DATA WAREHOUSE USING TREE MINING AND EVOLUTIONARY COMPUTATION

Selection of a proper set of views to materialize plays an important role indatabase performance. There are many methods of view selection which uses different techniques and frameworks to select an efficient set of views for materialization. In this paper, we present a new efficient, scalable method for view selection under the given storage constraints using a tree mining approach and evolutionary optimization. Tree mining algorithm is designed to determine the exact frequency of (sub)queries in the historical SQL dataset. Query Cost model achieves the objective of maximizing the performance benefits from the final view set which is derived from the frequent view set given by tree mining algorithm. Performance benefit of a query is defined as a function of queryfrequency, query creation cost, and query maintenance cost. The experimental results shows that the proposed method is successful in recommending a solution which is fairly close to optimal solution

A design methodology for data warehouses

The objective of this work is to develop a design methodology for data warehouses. It is based on the three level modeling approach with emphasis on conceptual modeling. Logical design to the relational model and physical tuning in this environment will also be treated