We discuss the design and implementation of the O 2 Views object-oriented database view mechanism, which allows the redeenition of both the structure and the behavior of objects stored in a database. The data model extended with views is rst given and then the functionalities of the prototype implementing it are presented. The paper focuses on the requirements for the implementation of an objec...

The role of materialized views is becoming vital in today’s distributed Data warehouses. Materialization is where parts of the data cube are pre-computed. Some of the real time distributed architectures are maintaining materialization transparencies in the sense the users are not known with the materialization at a node. Usually what all followed by them is a cache maintenance mechanism where t...

Materialization is a useful abstraction pattern that can be identified in many application settings. Intuitively, materialization is the relationship between a class of categories (e.g., models of cars) and a class of more concrete objects (e.g., individual cars). This paper gives a quasi-formal semantic definition of materialization in terms of the usual is-a and isof abstractions, and of a cl...

We consider a variant of the view maintenance problem: How does one keep a materialized view up-todate when the view definition itself changes? Can one do better than recomputing the view from the base relations? Traditional view maintenance tries to maintain the materialized view in response to modifications to the base relations; we try to “adapt” the view in response to changes in the view d...

ViSMA (Views Supported by Mobile Agents) is a prototype set of extendible mobile-agent based services that allow the definition, materialization, maintenance and sharing of views created over remote web-accessible databases. The system’s primary goal is to support mobile clients carrying lightweight devices of various connectivity and resources such as portable computers and PDAs by being compl...

In this paper, we are dealing with the topic of view maintenance which consists of maintaining materialized views in response to data modifications on the data sources. We propose an incremental method to maintain XML views. This is achieved by defining first how to store XML views, which may be obtained over different data sources, in a relational DBMS. The identifiers used to store the view d...

The materialization of views promotes the reduction of multidimensional queries’s execution time. However, this materialization has an associated cost that may exceed the cost constraints of a given environment, characterizing the view selection problem (VSP). VSP consists in selecting the best views given a certain cost threshold. Several solutions have been proposed in the literature to try a...

In relational databases a view definition is a query against the database, and a view materializ-ation is the result of applying the view definition to the current database. A view materialization over a database may change as relations in the database undergo modifications. Several problems concerning views are considered, many of which are shown to be hard (NP-complete or even-complete). Each...