Conventional object-oriented database (OODB) systems follow a class-based approach to model real world entities and their relationships, which imposes several difficulties when more advanced "dynamic functions&qu...
详细信息
Conventional object-oriented database (OODB) systems follow a class-based approach to model real world entities and their relationships, which imposes several difficulties when more advanced "dynamic functions" are needed by the applications. One of such dynamic functions is conceptual clustering - the ability to dynamically group a set of existing objects together as a higher-level abstract object (called a "cluster"). The conceptual clustering model (CCM) that we have defined is an extension to current object-oriented models, which facilitates the modeling of dynamic, evolving, and/or ad hoc object clusters through a well-devised clustering mechanism that incorporates "roles". This paper presents the advanced features of CCM, along with its associated query language facilities devised for supporting general definition and access of clusters (and roles). An experimental prototype of the CCM has been constructed on top of a persistent object storage manager, running on a Sun4 workstation.
In this paper, we consider the framework of "complex" information systems, related to biology, geographical information, multimedia, etc. Apart from being inherently complex, objects of these domains are evo...
详细信息
Semantic relations between concepts or data are common modelling devices in various knowledge representation approaches. Fuzzy relations can be defined as fuzzy subsets of the cartesian product of a number of domains,...
详细信息
We present a theorem-prover based analysis tool for object-oriented database systems with integrity constraints. object-oriented database specifications are mapped to higher-order logic (HOL). This allows us to reason...
详细信息
ISBN:
(纸本)3540657037
We present a theorem-prover based analysis tool for object-oriented database systems with integrity constraints. object-oriented database specifications are mapped to higher-order logic (HOL). This allows us to reason about the semantics of database operations using a mechanical theorem prover such as Isabelle or PVS. The tool can be used to verify various semantics requirements of the schema (such as transaction safety, compensation, and commutativity) to support the advanced transaction models used in workflow and cooperative work. We give an example of method safety analysis for the generic structure editing operations of a cooperative authoring system.
One of the differences between relational and object-oriented databases (OODB) is that attributes in OODB can be of a collection type (e.g. sets, lists, arrays, and bags) as well as a simple type (e.g. integer, string...
详细信息
One of the differences between relational and object-oriented databases (OODB) is that attributes in OODB can be of a collection type (e.g. sets, lists, arrays, and bags) as well as a simple type (e.g. integer, string). Consequently, explicit join queries in OODB may be based on collection attributes. We call this type of join Collection Join Queries. There are three different kinds of collection join queries, namely: Collection-Equi Join, Collection-Intersect join, and Sub-Collection Join. Basically, a collection-equi join query checks an equality of both collection operands, whereas a collection-intersect join query checks whether there is an intersection between the two join collection attributes. Sub-collection join queries check whether one collection is a sub-collection of the other. In this paper, we present parallel join algorithms for the above three collection join query types based on the sort-merge technique. Sonic of the proposed algorithms employ a nested-loop construct as well. We also outline the complexity of collection merging in the algorithm. Parallel join algorithms are normally composed of two stages, data partitioning and local join. For the data partitioning stage in collection-intersect and sub-collection join algorithms, we propose a 'Divide and Partial Broadcast' partitioning. The proposed join algorithms play an important role in parallel object-oriented query processing, due to their superiority over the conventional join methods, which are usually in a form of relational division, and also the inefficiency of original join predicates processing.
object-oriented databases has rich semantics, which enables the definition of various relationships among objects. Sharing levels and composition types necessitate the definition of whether, and to which extent, shoul...
详细信息
Changes in the real world may require both the database population and the database schema to evolve. Particularly, this is the case in CAD/CAM and CASE database systems, in which the design objects constantly evolve ...
详细信息
Collection join queries are join queries based on collection attributes (i.e. non-atomic attributes), which are common in object-oriented databases. We have identified three different kinds of collection join queries,...
详细信息
Collection join queries are join queries based on collection attributes (i.e. non-atomic attributes), which are common in object-oriented databases. We have identified three different kinds of collection join queries, namely;cullection-equijoin,collection-intersectjoin, andsub-collectionjoin. In this paper, we propose parallel join algorithms for these three collection join query types based on a combination of sort and hash methods, which we callparallel sort-hash, collection join algorithms. The proposed join algorithms play an important role in parallel object-oriented query processing, due to their superiority over the conventional join methods which are usually in a form of relational division, and also the inefficiency of the original join predicate processing. In our implementation of these algorithms on a shared-memory machine, we show that the combination between sort and hash methods is proven to be better than the conventional sort-merge and nested-loop based parallel join processing
Index structures are often used to support search operations in large databases. Many advanced database application domains such as spatial databases, multimedia databases, temporal databases, and object-oriented data...
详细信息
ISBN:
(纸本)0909925836
Index structures are often used to support search operations in large databases. Many advanced database application domains such as spatial databases, multimedia databases, temporal databases, and object-oriented databases, call for index structures that are specially designed and tailored for the domains. Interestingly, in each of these domains, we find methods that are based on one distinct structure - the B-tree. Invented some thirty years ago, the B-tree has been challenged repeatedly, but has retained its competitiveness. In this paper, we first give a quick review of B-trees. We then present its adaptations to various domains. For each domain, we present representative B-tree-based structures and their search operations. We conclude that the B-tree is truly an ubiquitous structure that has stood the test of times with wide acceptance in many domains.
The object-oriented data model is predicted to be the heart of the next generation of database systems. Users want to move from old legacy databases into applying this new technology that provides extensibility and fl...
详细信息
ISBN:
(纸本)0769513034
The object-oriented data model is predicted to be the heart of the next generation of database systems. Users want to move from old legacy databases into applying this new technology that provides extensibility and flexibility in maintenance. However, a major limitation on the wide acceptance of object-oriented databases is the amount of time. and money invested on existing database applications, which are based on conventional legacy systems, Users do not want to loose the huge amounts of data present in conventional databases. This paper presents a novel approach to transform a given conventional database into an object-oriented database. It is assumed that the necessary characteristics of the conventional database to be re-engineered are known and available. The source of these characteristics might be the data dictionary and/or an expert in the given conventional database. We implemented a system that builds an understanding of a given conventional database by taking these characteristics as input and produces the corresponding object-oriented database as output. The system derives a graph that summarizes the conceptual model. Links in the graph are classified into inheritance links and aggregation links. This classification leads to the class hierarchy. Finally, we handle the migration of data from the conventional database to the constructed object-oriented database.
暂无评论