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Security: Data not needed by local applications is not stored at the site, therefore no unnecessary security violations may exist.
But how can we carry out fragmentation? Fragmentation may be carried out as per the following rules:
a) Completeness: This rule makes sure that there is no loss of data while fragmentation. If a relation is decomposed into fragments, then every data item must appear in at least single fragment.
b) Reconstruction: This rule makes sure preservation of functional dependencies. It should be possible to describe a relational operation that will reconstruct the relation from its fragments.
c) Disjointness: A data item that shows in a fragment should not show in any other fragment. Though, a typical fragmentation known as vertical fragmentation is an exception to this rule. In vertical fragmentation the primary key attributes must be repeated to permit reconstruction of original relation.
This rule makes sure minimization of data redundancy. What are the dissimilar types of fragmentation?
What is meant by computing the closure of a set of functional dependency? The closure of F denoted by F + is the set of functional dependencies logically implied by F.
The Enhanced Entity Relationship Diagram (ERD) produced with a drawing or case tool. Your EERD must use a ''standard'' notation style such as Crows Foot or Chen. Please note that t
what are information system hirarchy?
Fragmentation: It is definite as partitioning of a relation into various fragments.Every fragment can be stored at a dissimilar site.
what is union compatable?
Update Anomaly : This anomaly is occurred due to data redundancy. Redundant information makes updates more complex since, for example, varying the name of the instructor of MCS-014
Group By clauses • It is used to group database tuples on the basis of definite common attribute value like as employees of a department. WHERE clause still can be used
Draw the precedence graph of the following schedule and determine whether the schedule is serializable. (Note that all instructions, except lock and unlock, are omitted. We assume
Which are the two ways in which entities can participate in a relationship? Total and partial are the two ways in which entities can participate in a relationship
INTRODUCTION Databases and database systems have become an essential part of our daily life. We encounter many activities that involve some interaction with a database almost
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