20 research outputs found
A comparative study of transaction management services in multidatabase heterogeneous systems
Multidatabases are being actively researched as a relatively new area in which many aspects are not yet fully understood. This area of transaction management in multidatabase systems still has many unresolved problems. The problem areas which this dissertation addresses are classification of multidatabase systems, global concurrency control, correctness criterion in a multidatabase environment, global deadlock detection, atomic commitment and crash recovery. A core group of research addressing these problems was identified and studied. The dissertation contributes to the multidatabase transaction management topic by introducing an alternative classification method for such multiple database systems; assessing existing research into
transaction management schemes and based on this assessment, proposes a transaction
processing model founded on the optimal properties of transaction management identified during
the course of this research.ComputingM. Sc. (Computer Science
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Execution Autonomy in Distributed Transaction Processing
We study the feasibility of execution autonomy in systems with asynchronous transaction processing based on epsilon-serializability (ESR). The abstract correctness criteria defined by ESR are implemented by techniques such as asynchronous divergence control and asynchronous consistency restoration. Concrete application examples in a distributed environment, such as banking, are described in order to illustrate the advantages of using ESR to support execution autonomy
Mobile Transaction Supports for DBMS
National audienceIn recent years data management in mobile environments has generated a great interest. Several proposals concerning mobile transactions have been done. However, it is very difficult to have an overview of all these approaches. In this paper we analyze and compare several contributions on mobile transactions and introduce our ongoing research: the design and implementation of a Mobile Transaction Service. The focus of our study is on execution models, the manner ACID properties are provided and the way geographical movements of hosts (during transaction executions) is supported
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A Formal Characterization of Epsilon Serializability
Epsilon Serializability (ESR) is a generalization of classic serializability (SR). ESR allows some limited amount of inconsistency in transaction processing (TP), through an interface called epsilon-transactions (ETs). For example, some query ETs may view inconsistent data due to non-SR interleaving with concurrent updates. In this paper, we restrict our attention to the situation where query-only ETs run concurrently with consistent update transactions that are SR without the ETs. This paper presents a formal characterization of ESR and ETs. Using the ACTA framework, the first part of this characterization formally expresses the inter-transaction conflicts that are recognized by ESR and, through that, defines ESR, analogous to the manner in which conflict-based serializability is defined. The second part of the paper is devoted to deriving expressions for: (1) the inconsistency in the values of data -- arising from ongoing updates, (2) the inconsistency of the results of a query ““ arising from the inconsistency of the data read in order to process the query, and (3) the inconsistency exported by an update ET - arising from ongoing queries reading uncommitted data produced by the update ET. These expressions are used to determine the preconditions that ET operations have to satisfy in order to maintain the limits on the inconsistency in the data read by query ETs, the inconsistency exported by update ETs, and the inconsistency in the results of queries. This determination suggests possible mechanisms that can be used to realize ESR