作者：
Sheng, Yeh-HengUniSQL
Inc. 9380 Research Blvd. Kaleido II AustinTX78759 United States
A non-deterministic deductive database language IDLOG that employs tuple-identifiers in DATALOG (with negation) was proposed in [She90b] to enhance the expressive power of deductive database languages. It was shown th...
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An active database system reacts to a set of external events such as a timer interrupt or access to a particular object in the database. A trigger is a general mechanism for active data management, both in the context...
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An active database system reacts to a set of external events such as a timer interrupt or access to a particular object in the database. A trigger is a general mechanism for active data management, both in the context of a centralized system or a distributed system (including that of autonomous and cooperating agents). It consists of three parts; event specification, integrity constraint specification, and action specification. The event specification in a trigger is a set of events which will cause the condition in the constraint specification to be checked. If the condition is true, the actions in the action specification will be initiated. In this paper, we develop a framework for supporting triggers in object-oriented database systems. The framework consists of a categorization for each of the three components of a trigger. The framework is first cast in the context of the relational model of data, and is then extended to account for object-oriented concepts that constitute an object-oriented data model, including nested objects, methods, and inheritance hierarchy.
The authors investigate principles of translating relational queries to hierarchical queries. Instead of using a specific hierarchical database system they abstract a generic hierarchical database system (GHDBS) which...
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The authors investigate principles of translating relational queries to hierarchical queries. Instead of using a specific hierarchical database system they abstract a generic hierarchical database system (GHDBS) which has properties common to database systems whose schema contain hierarchical structures. Principles of query translation with GHDBS as the receiving database system are developed. Rules that guarantee the correctness of the translated queries are described. Rules are provided that can guarantee a minimum number of target queries in a case when a user-submitted source query needs to be translated to multiple target queries.< >
The problem of maintaining transaction consistency in MDBSs (multidatabase systems) using quasi-realizable executions is addressed. The aspects of transaction consistency that can be effectively maintained by quasi-se...
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The problem of maintaining transaction consistency in MDBSs (multidatabase systems) using quasi-realizable executions is addressed. The aspects of transaction consistency that can be effectively maintained by quasi-serializable executions are identified. A technique for preventing possible violation of those aspects of transaction consistency that are not ensured by quasi-serializable executions is proposed.< >
A scheduler producing quasi-serializable executions for concurrency control in multidatabase systems (MDBSs) is presented. An algorithm is proposed which ensures quasi-serializability by controlling submissions of glo...
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A scheduler producing quasi-serializable executions for concurrency control in multidatabase systems (MDBSs) is presented. An algorithm is proposed which ensures quasi-serializability by controlling submissions of global transactions. The algorithm groups global transactions in such a way that transactions in a group affect each other in a partial order. Transaction groups are executed separately and in a consistent order at all local sites. The algorithm differs from the others in that it does not violate local autonomy, provides a high degree of concurrency, and is globally deadlock-free.< >
As applications have grown more sophisticated, they have placed greater demands on underlying database technology. In this paper we examine some of the shortcomings of conventional database technologies in the face of...
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Replication is useful in multidatabase systems (MDBSs) because, as in traditional distributed database systems, it increases data availability in the presence of failures and decreases data retrieval costs by reading ...
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Examines the problem of performing the atomic commitment of global transactions in multi-database system environments, where autonomous local database systems are integrated into a global database system. It is shown,...
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Examines the problem of performing the atomic commitment of global transactions in multi-database system environments, where autonomous local database systems are integrated into a global database system. It is shown, that if the autonomy of the local database systems is preserved, it is impossible to perform atomic commitment in general, even under the assumption that there are no system failures. It is also shown that even when it is assumed that all local database systems use strict two phase locking (an assumption useful for performing global concurrency control), atomic commitment is impossible if even a single system failure can occur.< >
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