The quickly increasing number of spatio-temporal applications in fields like environmental monitoring, geology and mobile communication is a new challenge to the development of geodatabases. However, the query functio...
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The quickly increasing number of spatio-temporal applications in fields like environmental monitoring, geology and mobile communication is a new challenge to the development of geodatabases. However, the query functionality of today's geo-information systems is still limited to the thematic attributes of spatial objects and to spatial 2-D objects. This article reports on GeoToolKit, an object-oriented geo-database kernel system developed at Bonn University to support 3-D/4-D geological applications. GeoToolKit is not a GIS-in-a-box package, but rather a library of C + + classes that allows the incorporation of spatio-temporal functionality within an application. Being a component toolkit, it encourages the development and deployment of re-usable and open software. The history, concepts and implementation of GeoToolKit are discussed in detail. Performance tests underline the practicability of the concepts. Extensions to and experiences with GeoToolKit applications like GeoStore, GeoWeb and WellStore are presented. Finally, we give an outlook on our future research introducing GeoToolKit as a 3-D/4-D database component within a network of distributed and mobile geo-information services.
In this paper, we propose a new index structure for object-oriented databases. The main idea of this is a graph structure, called a signature graph, which is constructed over a signature file generated for a class and...
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ISBN:
(纸本)9781581138122
In this paper, we propose a new index structure for object-oriented databases. The main idea of this is a graph structure, called a signature graph, which is constructed over a signature file generated for a class and improves the search of a signature file dramatically. In addition, the signature files (accordingly, the signature graphs) can be organized into a hierarchy according to the nested structure (called the aggregation hierarchy) of classes in an object-oriented database, which leads to another significant improvements.
We introduce a model to implement incremental update of views. The principle is that unless a view is accessed, the modification related to the view is not computed. This modification information is used only when vie...
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We introduce a model to implement incremental update of views. The principle is that unless a view is accessed, the modification related to the view is not computed. This modification information is used only when views are updated. Modification information is embodied in the classes (including inheritance classes and nesting classes) that derive the view. We establish a modify list consisted of tuples (one tuple for each view which is related to the class) to implement view update. A method is used to keep views from re-update.
Key words object-oriented database - incremental computation - view-computation - engineering information system
CLC number TP 391
Foundation item: Supported by the National Natural Science Foundation of China(60235025)
Biography: Guo Hai-ying (1971-), female, Ph. D, research direction: CAD and engineering information system.
This research focuses on the study of crop scene visualization based on crop simulation and knowledge engineering, techniques. Corn data are measured in the field of Luancheng, Hebei Province and Shunyi, Beijing City....
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ISBN:
(纸本)0780387422
This research focuses on the study of crop scene visualization based on crop simulation and knowledge engineering, techniques. Corn data are measured in the field of Luancheng, Hebei Province and Shunyi, Beijing City. In the study of 3D simulation of crop realistic structure, the object-oriented knowledge database of crop realistic structure is in further development. The data structure of realistic scene used here can organize the whole visualization process well. With the appearance of the realistic structure model of the quantity remote sensing, the field of crop visualization study is more and more important. During the process of studying visualization, the object-oriented 3D visualization data model arises, which is used as the formation of the crop realistic structure. 3D visualization data model will be applied to the description of crop structure successfully by object-oriented design and confirming the geometrical and logical relation. In the paper, we have the description and computer simulation of the scene of vegetation as a main clue. We are working on the data organization by design principle of objected-oriented DBMS. We use the corn scene data from the experiments in Shunyi, Beijing City, 2001 as an example to build the remote sensing data model. Then, we produce the 3D model usina L-system and present 3D scene of summer corn on the computer to show the visualization.
For a company with many databases in different data models, it is necessary to consolidate them into one data model interchangeable and present data in one data model concurrently to users. The benefit is to let user ...
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For a company with many databases in different data models, it is necessary to consolidate them into one data model interchangeable and present data in one data model concurrently to users. The benefit is to let user stick to his/her own data model to access database in another data model. This paper presents a semantic metadata to preserve database constraints for data materialization to support user's view of database on an ad hoc base. The semantic metadata can store the captured semantics of a relational or an object-oriented database into classes and stored procedures triggered by events. The stored constraints and data can be materialized into a target database upon user request. The user is allowed to perform the data materialization many times alternatively. The process can provide a relational as well as an objectoriented view to the users simultaneously. This concurrent data materialization function can be applied to data warehouse to consolidate heterogeneous database into a fact table in a data model of user's choice. Furthermore, a user can obtain either a relational view or an object-oriented view of the same dataset of an object-relational database interchangeably.
Detecting the possibility of inference attacks is necessary in order to keep a database secure. Inference attacks mean that a user tries to infer the result of an unauthorized queries to the user. For method schemas, ...
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Detecting the possibility of inference attacks is necessary in order to keep a database secure. Inference attacks mean that a user tries to infer the result of an unauthorized queries to the user. For method schemas, which are a formal model of object-oriented databases, it is known that the security problem against inference attacks is decidable in polynomial time in the size of a given database instance. However, when the database instance or authorization has slightly been updated, it is not desirable to check the entire database again for efficiency. In this paper, we propose several sufficient conditions for update operations to preserve the security. Furthermore, we show that some of the proposed sufficient conditions can be decided much more efficiently than the entire security check. Thus, the sufficient conditions are useful for incremental security checking.
The problem of index configuration is an important topic for database system performance and has been extensively investigated for relational database Management Systems (DBMS). By contrast, the problem of index alloc...
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The problem of index configuration is an important topic for database system performance and has been extensively investigated for relational database Management Systems (DBMS). By contrast, the problem of index allocation for object-oriented DBMS (OODBMS) has been considered only from a theoretical point of view and no practical development of any tool for commercial OODBMS has been reported. In this paper, we investigate the problem of index configuration in the framework of a commercially available OODBMS, We first identify the features that characterize such OODBMS and we develop two cost models: the first extends the generic cost model presented by Gardarin ed al. (Proceedings of the 22nd International Conference on Very Large Data Bases, 1996;378-389), the second is an analytical cost model tailored to the OODBMS at hand, Both cost models have been validated by comparing the estimated costs and the actual costs observed from the system. The comparison has shown that both models are quite accurate. Using the proposed cost models, we have also developed an algorithm for the efficient index allocation on a given path, given a workload specified in terms of operation frequencies, Even though our algorithm has been developed for a specific OODBMS, we believe that it can be easily tailored to other OODBMS and persistent programming languages. Copyright (C) 2000 John Wiley & Sons, Ltd.
In this paper, a concurrency control scheme to increase concurrency among methods in object-oriented database systems (OODBs) is presented. The author is concerned with all types of access to an object: instance acces...
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In this paper, a concurrency control scheme to increase concurrency among methods in object-oriented database systems (OODBs) is presented. The author is concerned with all types of access to an object: instance access and class definition access. For instance access, the proposed work has the following characteristics. First, construction of commutativity relation among methods can be automated. Second, it provides more concurrency by taking attributes as locking granularity. Third, deadlocks due to lock escalation can be reduced. Finally, concurrency is increased further with the use of run-time information. For class definition access, the proposed work allows class definition access methods to run concurrently by taking fine granularity. The proposed work also allows more parallelism between class definition access methods and instance access methods. For the performance evaluation of the proposed scheme, a simulation model is constructed. Using this model, the proposed technique is then compared with the two existing techniques. The performance studies show that the proposed scheme is superior to existing works. (C) 2000 Elsevier Science Inc. All rights reserved.
Formal semantics of OQL in terms of object algebra, such as quantification, mapping, selection, unnesting or partitioning, developed by the author is defined, and it is shown in multiple examples that OQL queries can ...
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ISBN:
(纸本)3540200479
Formal semantics of OQL in terms of object algebra, such as quantification, mapping, selection, unnesting or partitioning, developed by the author is defined, and it is shown in multiple examples that OQL queries can be easily expressed by means of this algebra. As a result, an OQL query can be mechanically translated into the corresponding object algebra expression, which can be further optimized and executed.
Parallel query processing is one of the research emphases of the parallel database, but the traditional parallel query processing techniques can not capture the intrinsic characteristic of object-oriented database and...
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Parallel query processing is one of the research emphases of the parallel database, but the traditional parallel query processing techniques can not capture the intrinsic characteristic of object-oriented database and its query, so the efficiency of the traditional techniques is low. In this paper, according to the characteristic of the object-oriented database and its query a series of parallel query processing techniques for object-oriented database are proposed, including the stage-by-stage executing strategy, the class-based hybrid data placement strategy, the mark-based data operation parallel executing algorithm and the semi-join-based parallel query processing algorithm. The results of performance evaluation are given.
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