This paper deals with modelling constraints in object-oriented databases, with emphasis given on exceptions. Constraints are restrictions on properties and relations of database objects that ensure the integrity of da...
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ISBN:
(纸本)3540587861
This paper deals with modelling constraints in object-oriented databases, with emphasis given on exceptions. Constraints are restrictions on properties and relations of database objects that ensure the integrity of data. Therefore, they should be obeyed by every object, but as in real-life, there are some exceptions to this ruler object-oriented databases provide rich semantic constructs, adequate to model real-world relations. Inheritance of constraints in object-oriented databases has been treated in a completely mandatory way, providing no room for exceptions. In this paper, an object-oriented constraint representation scheme is presented, along with a methodology for modelling constraint exceptions. Finally, an algorithm is described that ensures correct runtime resolution of constraint applicability. Since business is not in abstract, but in real-world, business database modelling would be greatly benefited from a tool that allows both a clear definition and an efficient enforcement of constraints with exceptions.
In this paper a semantic approach for the specification and the management of databases with evolving schemata is introduced. It is shown how a general object-oriented model for schema versioning and evolution can be ...
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ISBN:
(数字)9783540449577
ISBN:
(纸本)3540677976
In this paper a semantic approach for the specification and the management of databases with evolving schemata is introduced. It is shown how a general object-oriented model for schema versioning and evolution can be formalized;how the semantics of schema change operations can be defined;how interesting reasoning tasks can be supported, based on an encoding in description logics.
The paper focuses on the indexing on non-primitive (complex) values of attributes in an object management system. A new index structure for indexing on set (multivalued) attributes is proposed. This structure is based...
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ISBN:
(纸本)0818681306
The paper focuses on the indexing on non-primitive (complex) values of attributes in an object management system. A new index structure for indexing on set (multivalued) attributes is proposed. This structure is based an a partial order imposed on the values of the indexed attribute, which are subsets of a set of primitive values. It is shown that the proposed index allows the system to efficiently perform typical set operators that are postulated to be applied in object query languages (is-equal, is-subset, is-superset), without performing any costly operations on lists of object identifiers that would be necessary in traditional index structures. The new index structure called partial-order tree, is described and algorithms performing the set operators are outlined.
Many database applications require the storage and manipulation of different versions of data objects. However, current database systems do not support versioning well. Each application area treats versions in its own...
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ISBN:
(纸本)9783540550150
Many database applications require the storage and manipulation of different versions of data objects. However, current database systems do not support versioning well. Each application area treats versions in its own way, and these ways are usually incompatible with each other. We show how this incompatibility can be resolved by separating the physical, conceptual, and logical levels of versioning. We develop a version specification language at the conceptual level, and a multidimensional specification language at the logical level. By encoding the logical versioning semantics of an application into orthogonal dimensions, we generalize the ideas of historical and temporal databases to arbitrary object-oriented databases. The result is a unified, application-independent treatment of versioning.
This paper presents a novel approach to transform an existing object-oriented database into XML. The major motivation to carry out this study is the fact that it is necessary to facilitate platform independent exchang...
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ISBN:
(纸本)9781424414994
This paper presents a novel approach to transform an existing object-oriented database into XML. The major motivation to carry out this study is the fact that it is necessary to facilitate platform independent exchange of the content of objectorienteddatabases. There are more common features between the object-oriented model and XML and thus the mapping from object-oriented databases into XML is less problematic. To achieve the mapping, what we call the object graph is derived based on characteristics of the object-oriented schema;it simply summarizes and includes all nesting and inheritance links, which are the basics of the object-oriented model. Then, the inheritance is simulated in terms of nesting to get a simulated object graph. This way, everything in a simulated object graph is directly representable in XML format. Finally, we handle the mapping of the actual data from the object-oriented database into corresponding XML document(s).
For various predictable and unpredictable reasons, objects in object-oriented databases need to change upon an on-going basis. The ability to provide a mechanism to manage the dynamically changing objects is a common ...
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In this paper, we present a model that facilitates view maintenance within object-oriented databases. For that purpose, we differentiate between two categories of classes, base classes and brother classes. While the f...
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ISBN:
(纸本)354061656X
In this paper, we present a model that facilitates view maintenance within object-oriented databases. For that purpose, we differentiate between two categories of classes, base classes and brother classes. While the former constitute the actual database, the latter are introduced to hold virtual database, i.e., views derived from base classes. To achieve incremental view update, we introduce a modification list into each base class. A series of algorithms are developed to serve the purpose. Finally it happened that, view maintenance within object-oriented databases subsumes that within the nested and hence conventional relational models.
In t’his paper, we present a view model for object-oriented databases that extends in various directions view models typical of relational databases. In particular, the definition language allows views to be defined ...
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This paper describes work carried out on a model for the versioning of class definitions in an object-oriented database. By defining update and backdate functions on attributes of the previous and current version of a...
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In this paper, we present a locking-based concurrency control scheme for object-oriented databases (OODBs). The proposed scheme deals with class hierarchies in OODBs. Our scheme is based on implicit locking but design...
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ISBN:
(纸本)3540000283
In this paper, we present a locking-based concurrency control scheme for object-oriented databases (OODBs). The proposed scheme deals with class hierarchies in OODBs. Our scheme is based on implicit locking but designed to require less locking overhead than implicit locking for all types of accesses to OODBs. Our scheme makes use of intelligent method to reduce locking overhead. Especially, our scheme utilizes only structural information of OODBs so that extra information to reduce locking overhead is not necessary. We also prove theoretically that our scheme performs better than implicit locking.
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