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Define physical and logical data independence. How does this architecture help in achieving these?
Data independence entails that change in one view must not need a change in the view(s) above. There are two sorts of data independence: logical and physical. The meaning of Logical data independence is that the conceptual view can be changed without influencing the existing external view, that is a given record may be spilt or combined along with other records but the external views need not be modified to reflect this. The meaning of Physical data independence is that the physical storage structures or devices employed to store the data can be changed without effecting the existing conceptual view or external view, that is if earlier indexed sequential files are employed to store data and then the B- trees are used, even then the upper layers must not be effected.
Describe the storage structure of indexed sequential files and their access method. Ans: Index offers a lookup capability to rapidly reach the vicinity of the desired record.
Give an example of Object Representation For illustration, consider the implementation of a social security number within an employee object that is shown in Figure. The soci
A relation instance indicates as r is a collection of tuples for a given relational schema at a exact point of time. A relation state r of the relation schema R (A 1 ,A 2 ,.....
What is an Index? An index is a small table having only two columns. The first column has a copy of the primary or candidate key of a table and the second column having a set o
What is a view? How it is related to data independence? A view might be thought of as a virtual table, that is, a table that does not really exist in its own right but is inste
which component of DBMS can be embedded in a program? The data manipulation language (DML) is a component which is embedded in a program.
Explain different categories of failures that occur in Oracle database? Categories of Failures - In Oracle database subsequent types of failures can occurred: Statement Failu
What is trigger Triggers are statements that are implemented automatically by the system as the side effect of a change to the database.
Explain the term- Query. Queries are used to repossess and show specific records in a table. They can also be used to show specific fields of specific records, which meet the co
What are the components of storage manager? The storage manager components include a) Authorization and integrity manager b) Transaction manager c) Buffer manager d
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