distributedDatabase[1]

distributedDatabase[1] - Chapter 19 Distributed DBMSs -...

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Chapter 19 Distributed DBMSs - Concepts and Design Transparencies
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3 Concepts Distributed Database A logically interrelated collection of shared data (and a description of this data), physically distributed over a computer network. Distributed DBMS Software system that permits the management of the distributed database and makes the distribution transparent to users. Collection of logically-related shared data. Data split into fragments. Fragments may be replicated. Fragments/replicas allocated to sites. Sites linked by a communications network. Data at each site is under control of a DBMS. DBMSs handle local applications autonomously. Each DBMS participates in at least one global application.
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5 Distributed DBMS - Distributed Processing A centralized database that can be accessed over a computer network.
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7 Parallel DBMS A DBMS running across multiple processors and disks designed to execute operations in parallel, whenever possible, to improve performance . Based on premise that single processor systems can no longer meet requirements for cost-effective scalability, reliability, and performance. Parallel DBMSs link multiple, smaller machines to achieve same throughput as single, larger machine, with greater scalability and reliability. Main architectures for parallel DBMSs are: Shared memory Shared disk Shared nothing.
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10 Advantages of DDBMSs Organizational Structure Shareability and Local Autonomy Improved Availability Improved Reliability Improved Performance Economics Modular Growth Disadvantages of DDBMSs Complexity Cost Security Integrity Control More Difficult Lack of Standards Lack of Experience Database Design More Complex Types of DDBMS Homogeneous DDBMS All sites use same DBMS product. Much easier to design and manage. Approach provides incremental growth and allows increased performance. Heterogeneous DDBMS Sites may run different DBMS products, with possibly different underlying data models. Occurs when sites have implemented their own databases and integration is considered later. Translations required to allow for: Different hardware. Different DBMS products. Different HW and different DBMS products. Typical solution is to use gateways .
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15 Open Database Access and Interoperability Open Group has formed a Working Group to provide specifications that will create database infrastructure environment where there is: Common SQL API that allows client applications to be written that do not need to know vendor of DBMS they are accessing. Common database protocol that enables DBMS from one vendor to communicate directly with DBMS from another vendor without the need for a gateway. A common network protocol that allows communications between different
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distributedDatabase[1] - Chapter 19 Distributed DBMSs -...

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