Define transparency. Explain the layers of transparencies in distributed database design in brief.
Definitaion Of Transparency : Transparency means that the DDBMS hides all the added complexities of distribution, allowing users to think that they are working with a single centralized system. DDBMS should be Distribution Transparent. That is, the user need not be aware of how data is fragmented or the physical storage locations of fragments.
layers of transparencies are:
Fragmentation transparency:
Fragmentation is the highest level of distribution transparency. If fragmentation transparency is provided by the DDBMS, then the user does not need to know that the data is fragmented, As a result, database accesses are based on the global schema,. so the user does not need to specify fragment names or data locations.
Location transparency:
Location is the middle level of distribution transparency. With location transparency, the user must know how the data has been fragmented but still does not have to know the location of the data.
Replication transparency:
Closely related to location transparency is replication transparency, which means that the user is unaware of the replication of fragments. Replication transparency is implied' by location transparency.
Naming transparency:
Naming transparency means that a unique name is provided for each object in the database. The DDBMS must ensure that no two sites create a database object with the same name. central name server is used to solve this problem. This server has the responsibility for ensuring uniqueness of all names in the system.
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