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Topic: Transparencies in a Distributed DBMS
Name: SREEJA SETH
University Roll No: 11700220085
College Roll No: IT2020/005
Paper Name: Distributed Systems
Paper Code: PEC-IT601B
Continuous Assessment – 1 (Academic Session: 2023 – 2024)
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Presentation Outline
• Transparency In Distributed DBMS
• Different Aspects of Transparency in Distributed DBMS
• Location Transparency
• Fragmentation Transparency
• Replication Transparency
• References
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Transparency In Distributed DBMS
Transparency in DDBMS refers to the transparent distribution of information to the user from the
system.
Transparency aids in covering the information that the user is to apply.
Distribution transparency is the property of distributed databases by the virtue of which the
internal details of the distribution are hidden from the users.
The DDBMS designer may choose to fragment tables, replicate the fragments and store them at
different sites. However, since users are oblivious of these details, they find the distributed
database easy to use like any centralized database.
Transparency in for the DBMS stands separation of high level semantics of the system from the
low-level implementation issue.
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Different Aspects of Transparency in Distributed
DBMS
The three aspects of transparency in distribution are :
 Location transparency
 Fragmentation transparency
 Replication transparency
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Location Transparency
Clients should see a uniform file name space. Files or groups of files may be relocated without
changing their pathnames.
This property is important to support the movement of the resources and the availability of services.
The location and access transparencies together are sometimes referred as Network transparency.
If this type of transparency is provided by DDBMS, then it is necessary for the user to know how the
data has been fragmented, but knowing the location of the data is not necessary.
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Fragmentation Transparency
Fragmentation transparency states that the fragments that are created to store the data in distributed
manner should remain transparent and all the data management work required to control the
fragments should be done by the system, not by the user.
 In this task, when a user puts a query, the global query is distributed in many sites to fetch data from
fragments and this data is put together at the end to generate the result.
The system ensures that the total procedure of query decomposition and re-composition should be
transparent to the user.
The user does not have to be aware of fragmented data in this type of transparency, which is why
database accesses are based on the global schema.
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Replication Transparency
not by user.
The user should not have any doubt about whether the fetched data is coming from replicated copy of
the elation or from the actual copy of the relation.
 To achieve replication transparency the concurrency control protocol needs to be devised, which
assures that the update of data taking place in one copy should also be updated in other copies. In this
way, transparency regarding replicas of data can be maintained.
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References
• Principles of Distributed Database Systems, M.T. Ozsu and Padres, Prentice-Hall, 1991.
• Distributed Database Systems, D. Bell and J. Grimson, Addison Wesley, 1992.
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