In distributed databases, location transparency allows for database users,…
2016
In distributed databases, location transparency allows for database users, programmers and administrators to treat the data as if it is at one location. A SQL query with location transparency needs to specify :
- A.
Inheritances
- B.
Fragments
- C.
Locations
- D.
Local formats
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Correct answer: B
Answer: Fragments
Explanation: Location transparency means users and applications do not need to know the physical locations of data. In a distributed database, data is often split into logical pieces called fragments. With location transparency, a SQL query is written against the logical data (the fragments or relations), and the distributed DBMS finds and assembles the required fragments from the sites where they reside.
Inheritances: Refers to subtype/class relationships, not data location or distribution.
Locations: Requiring physical locations in queries would break location transparency, so this is not required.
Local formats: Relate to data representation differences across sites (heterogeneity), not to specifying where data fragments are located.
Summary: The query should refer to the logical fragments; the distributed DBMS handles mapping those fragments to their physical locations, preserving location transparency for the user.