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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?
Determine the advantage of object-orientation Finally, object-orientation has advantage of continuity throughout analysis, persistent representation and design implementation.
Explain P command in the respect of QBE? P: It is the command in which is used to print (logically display) the value of the attribute in whose cell it is writ
Give the two reasons for allowing concurrency
Complexity : A distributed DBMS that is available, reliable, and secure is inherently more difficult than a centralised DBMS. Though, adequate data replication is essential to have
Primary index A primary index is a file that has a sorted series of records having two columns: a block address for that key field in the data file; and the ordering key field.
what is entity in database system?
object oriented database
Consider a database schema consisting of four relations, whose schemas are: Product (maker, model, type) PC (model, speed, ram, hd, price) Laptop (model, speed, ram, hd, s
Data Fragmentation "Fragmentation includes decomposing the data in relation to non-overlapping component relations". Why do we require fragmenting a relation?
1. Create the tables for the play-scheme database as specified in the TMA. 2. Enter the data as given in the spreadsheet. 3. Create queries to retrieve specified information
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