scholarly journals A SURVIVABLE DISTRIBUTED DATABASE AGAINST BYZANTINE FAILURE

2017 ◽  
Vol 15 (2) ◽  
pp. 61-72
Author(s):  
D O ABORISADE ◽  
A S SODIYA ◽  
A A ODUMOSU ◽  
O Y ALOWOSILE ◽  
A A ADEDEJI
Keyword(s):  
Distributed Databases ◽  
Database Systems ◽  
Distributed Database ◽  
Critical Systems ◽  
Contributing Factors ◽  
Internal Factors ◽  
Wide Range ◽  
Byzantine Failure ◽  
Byzantine Failures ◽  
The Face

Distributed Database Systems have been very useful technologies in making a wide range of information available to users across the World. However, there are now growing security concerns, arising from the use of distributed systems, particularly the ones attached to critical systems. More than ever before, data in distributed databases are more susceptible to attacks, failures or accidents owing to advanced knowledge explosions in network and database technologies. The imperfection of the existing security mechanisms coupled with the heightened and growing concerns for intrusion, attack, compromise or even failure owing to Byzantine failure are also contributing factors. The importance of  survivable distributed databases in the face of byzantine failure, to other emerging technologies is the motivation for this research. Furthermore, It has been observed that most of the existing works on distributed database only dwelled on maintaining data integrity and availability in the face of attack. There exist few on availability or survibability of distributed databases owing to internal factors such as internal sabotage or storage defects. In this paper, an architecture for entrenching survivability of Distributed Databases occasioned by Byzantine failures is proposed. The proposed architecture concept is based on re-creating data on failing database server based on a set  threshold value.The proposed architecture is tested and found to be capable of improving probability of survivability in distributed database where it is implemented to  99.6%  from 99.2%. 

MULTI-KEY INDEX FOR DISTRIBUTED DATABASE SYSTEM

2005 ◽  
Vol 15 (02) ◽  
pp. 433-438
Author(s):  
MD. SHAZZAD HOSAIN ◽  
MUHAMMAD ABDUL HAKIM NEWTON
Keyword(s):  
Distributed Databases ◽  
Database Systems ◽  
Distributed Database ◽  
Index Model ◽  
Network Bandwidth ◽  
Distributed Database Systems ◽  
Efficient Access ◽  
Distributed Database System ◽  
Bit Vector ◽  
Centralized Database

In this paper we present a multi-key index model that enables us to search a record with more than one attribute values in distributed database systems. Indices provide fast and efficient access of data and so become a major aspect in centralized database systems. Most of the centralized database systems use B + tree or other types of index structures such as bit vector, graph structure, grid file etc. But in distributed database systems no index model is found in the literature. Therefore efficient access is a major problem in distributed databases. Our proposed index model avoids the query-flooding problem of existing system and thus optimizes network bandwidth.

AN EFFICIENT TEST FOR THE VALIDITY OF UNBIASED HYBRID KNOWLEDGE FRAGMENTATION IN DISTRIBUTED DATABASES

1992 ◽  
Vol 02 (04) ◽  
pp. 589-609 ◽  
Author(s):  
YANCHUN ZHANG ◽  
MARIA E. ORLOWSKA ◽  
ROBERT COLOMB
Keyword(s):  
Relational Databases ◽  
Distributed Databases ◽  
Database Design ◽  
Database Systems ◽  
Distributed Database ◽  
Knowledge Bases ◽  
Global Database ◽  
Efficient Test ◽  
Global Schema ◽  
Hybrid Knowledge

Knowledge bases contain specific and general knowledge. In relational database systems, specific knowledge is often represented as a set of relations. The conventional methodologies for centralized database design can be applied to develop a normalized, redundancy-free global schema. Distributed database design involves redundancy removal as well as the distribution design which allows replicated data segments. Thus, distribution design can be viewed as a process on a normalized global schema which produces a collection of fragments of relations from a global database. Clearly, not every fragment of data can be permitted as a relation. In this paper, we clarify and formally discuss three kinds of fragmentations of relational databases, and characterize their features as valid designs, and we introduce a hybrid knowledge fragmentation as the general case. For completeness of presentation, we first show an algorithm for the validity test of vertical fragmentations of normalized relations, and then extend it to the more general case of unbiased fragmentations.

scholarly journals From Classical to Fuzzy Databases in a Production Enterprise

2020 ◽  
Vol 26 (11) ◽  
pp. 1382-1401
Author(s):  
Izabela Rojek ◽  
Dariusz Mikołajewski ◽  
Piotr Kotlarz ◽  
Alžbeta Sapietová
Keyword(s):  
Business Intelligence ◽  
Relational Databases ◽  
Distributed Databases ◽  
Database Systems ◽  
Distributed Database ◽  
Data Warehouses ◽  
Distributed Database Systems ◽  
Fuzzy Database ◽  
The One ◽  
Global World

This article presents the evolution of databases from classical relational databases to distributed databases and data warehouses to fuzzy databases used in a production enterprise. This paper discusses characteristics of this kind of enterprise. The authors precisely define centralized and distributed databases, data warehouses and fuzzy databases. In the modern global world, many companies change their management strategy from the one based on a centralized database to an approach based on distributed database systems. Growing expectations regarding business intelligence encourage companies to deploy data warehouses. New solutions are sought as the demand for engineers' expertise continues to rise. The requested knowledge can be certain or uncertain. Certain knowledge does not any problems and is easy to obtain. However, uncertain knowledge requires new ways of obtaining, including the use of fuzzy logic. It is from where the fuzzy database approach takes its beginning. The above-mentioned strategies of a production enterprise were described herein as a case of special interest.

scholarly journals A Survey on Efficient Concurrency Control Algorithm in Distributed Database Systems

2019 ◽  
pp. 1176-1185
Author(s):  
Rebecca Nyasuguta Arika ◽  
W. Cheruiyot
Keyword(s):  
Concurrency Control ◽  
Control Algorithm ◽  
Distributed Databases ◽  
Database Systems ◽  
Distributed Database ◽  
Communication Overhead ◽  
Distributed Database Systems ◽  
Commit Protocols ◽  
Message Exchange ◽  
Transaction Commit

Transaction commit protocols help in reaching an agreement among the participating nodes when a transaction has to be committed or aborted. To initiate an agreement each participating node is asked to vote its decision on the operations on its transactional fragment. The participating nodes can decide to either commit or abort an ongoing transaction. In case of a node failure, the active participants take essential steps such as running the termination protocol to preserve database correctness. This paper sought to investigate the current distributed databases commit protocols such as 2PC and 3PC in order to pin-point their shortcomings. For instance, 2PC suffers from blocking of participant site in case of coordinator failure and increased latency due to forced writes of logs. On its part, 3PC suffers more communication overhead due to extra pre-commit phase. Based on these setbacks, an efficient protocol is suggested towards the end of this paper that it believed to address some of the challenges such as blocking and extra message exchange between communicating nodes.

Performance Evaluation of Distributed Database Systems

2014 ◽  
Vol 13 (9) ◽  
pp. 4859-4867
Author(s):  
Khaled Saleh Maabreh
Keyword(s):  
Performance Evaluation ◽  
System Performance ◽  
Operation Mode ◽  
Database Systems ◽  
Distributed Database ◽  
Evaluation Study ◽  
Distributed Database Systems ◽  
Different Types ◽  
Distributed Database System ◽  
Distributed Database Management

Distributed database management systems manage a huge amount of data as well as large and increasingly growing number of users through different types of queries. Therefore, efficient methods for accessing these data volumes will be required to provide a high and an acceptable level of system performance.  Data in these systems are varying in terms of types from texts to images, audios and videos that must be available through an optimized level of replication. Distributed database systems have many parameters like data distribution degree, operation mode and the number of sites and replication. These parameters have played a major role in any performance evaluation study. This paper investigates the main parameters that may affect the system performance, which may help with configuring the distributed database system for enhancing the overall system performance.

Democratization in Serbia: An Analysis of Rational Choice and Structuralist Explanations

2015 ◽  
Author(s):  
Dunja Apostolov-Dimitrijevic
Keyword(s):  
Rational Choice ◽  
Path Dependence ◽  
Theoretical Perspective ◽  
Political Leadership ◽  
Decisive Role ◽  
The Other ◽  
Internal Factors ◽  
Transitional Societies ◽  
The Face

This paper explains political democratization in Post-Milosevic Serbia, utilizing two different accounts of the democratization process: one rooted in the rational choice framework and the other in structuralism. While rational choice explains the decisive role of political leadership in overcoming path dependence, the structuralist explanations show the transnational linkages that encourage democratization in the face of domestic setbacks. This particular debate between the two types of explanations represents the larger debate concerning the role of internal factors and external linkages in propelling democratization in transitional societies. The paper concludes by integrating the two sets of explanations offered by each theoretical perspective, in order to develop a coherent understanding of Serbia's democratization.   Full text available at: https://doi.org/10.22215/rera.v9i1.240

scholarly journals Benchmarking scalability and elasticity of distributed database systems

2014 ◽  
Vol 7 (12) ◽  
pp. 1219-1230 ◽  
Author(s):  
Jörn Kuhlenkamp ◽  
Markus Klems ◽  
Oliver Röss
Keyword(s):  
Database Systems ◽  
Distributed Database ◽  
Distributed Database Systems
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