Lecture2 - are not affected. Location transparency Medium...

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Explain briefly the differences between the following levels of “distribution transparency“: o Fragmentation transparency o Location transparency o Local mapping transparency o No transparancy Transparency type Level SQL Statement requires Description Fragment name Location name Fragmentation transparency High No No It’s the highest level of distribution transparency. The user is not aware of the data fragmentation, fragment names, and data location. In another words, a user queries the database as if it was a centralized database, and the system does the necessary behind the scene work. If fragments change, queries and transactions
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Unformatted text preview: are not affected. Location transparency Medium Yes No A user is aware of the data fragmentation. However, he/she doesnt need to know the location of the data to be accessed. The system forwards the data access requests to the appropriate sites. Local mapping transparency Low Yes Yes Its the lowest transparency level. A user had to specify fragment name and location of the data to be accessed. No transparency None Yes Yes User is aware of fragments, locations and replications. A query would need to be modified as the data distribution changes....
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