The theory of database concurrency control
The theory of database concurrency control
Concurrency control and recovery in database systems
Concurrency control and recovery in database systems
Nested transactions: an introduction
Concurrency control and reliability in distributed systems
Combinatorial optimization: algorithms and complexity
Combinatorial optimization: algorithms and complexity
Triggered real-time databases with consistency constraints
Proceedings of the sixteenth international conference on Very large databases
Issues in real-time data management
Real-Time Systems - Special issue: real-time databases
Formal aspects of concurrency control in long-duration transaction systems using the NT/PV model
ACM Transactions on Database Systems (TODS)
Time-constrained transaction management
Time-constrained transaction management
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
Proceedings of the Fifth International Conference on Data Engineering
Real-Time Processing in Client-Server Databases
IEEE Transactions on Computers
Schema Evolution of an Object-Oriented Real-Time Database System for Manufacturing Automation
IEEE Transactions on Knowledge and Data Engineering
A Study of Concurrency Control in Real-Time, Active Database Systems
IEEE Transactions on Knowledge and Data Engineering
Real-Time and Active Databases: A Survey
ARTDB '97 Proceedings of the Second International Workshop on Active, Real-Time, and Temporal Database Systems
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Real-time database systems associate the concept of deadlines with transaction executions. Previous approaches use 驴best effort驴 techniques to schedule a given set of transactions to meet the deadlines as well as to ensure the consistency of the database. However, such approaches are inadequate for target applications which have 驴hard驴 real-time deadlines that need to be met in the event of crisis situations. In such cases, it is important to obtain contingency plans that may be invoked with guaranteed execution time characteristics. This paper presents an alternative model for real-time database systems in which deadlines are associated with 驴contingency驴 constraints rather than directly with transactions. Our approach leads to a predicate-based model that intrinsically incorporates both triggering and relative timing constraints regarding the transaction executions. We exhibit that selecting contingency plans with respect to various optimality criteria has inherent computational inefficiencies. We study the issues in scheduling of the selected plans with the focus on the contention among the transactions for data resources. Our results exhibit that the data contention, by itself, has a severe adverse impact on the schedulability of the deadline-constrained transactions. We discuss some of the practical implications of our results, and we suggest some counter-measures to handle the computational complexities.