21. How persistent programming languages differ from traditional programming languages?
Database languages differ from traditional programming languages in that they directly manipulate data that are persistent-that is, data that continue to exist even after the program terminated. Relation in a database and tuples in a relation are examples of persistent data. In contrast, the only persistent data that traditional programming languages directly manipulate are files.
22. Define atomic domains?
A domain is atomic if elements of the domain are considered to be indivisible units.
23. Define 1NF?
First normal form is one which requires that all attributes have atomic domains.
24. What is nested relational model?
The nested relational model is an extension of relational model in which domains may be either atomic or relation valued.
25. List some instances of collection types?
*sets
*arrays
*multisets
26. How to create values of structured type?
Constructor functions are used to create values of structured types. A function with the same name as a structured type is a constructor function for the structured type.
27. Write a query to define tables students and teachers as sub tables of people?
Create table students of student under people
Create table teachers of teacher under people
28. What is a homogeneous distributed database?
In homogeneous distributed databases, all sites have identical database management system software, are aware of one another, and agree to cooperate in processing user's requests.
29. What is a heterogeneous distributed database?
In a heterogeneous distributed database, different sites may use different schemas, and different dbms s/w.The sites may not be aware of one another, and they may provide only limited facilities for cooperation in transaction processing.
30. What are the two approaches to store relations in distributed database?
*Replication
*Fragmentation
31. What are the two different schemes for fragmenting a relation?
*horizontal
*vertical
32. What is horizontal fragmentation?
Horizontal fragmentation splits the relation by assuming each tuple of r to one or more fragments.
33. What is vertical fragmentation?
Vertical fragmentation splits the relation by decomposing the scheme R of relation r.
34. What are the various forms of data transparency?
*fragmentation transparency
*replication transparency
*location transparency
35. Define decision tree classifiers?
As the name suggests decision tree classifiers use a tree: each leaf node has an associated class, and each internal node has a predicate associated with it.
Database languages differ from traditional programming languages in that they directly manipulate data that are persistent-that is, data that continue to exist even after the program terminated. Relation in a database and tuples in a relation are examples of persistent data. In contrast, the only persistent data that traditional programming languages directly manipulate are files.
22. Define atomic domains?
A domain is atomic if elements of the domain are considered to be indivisible units.
23. Define 1NF?
First normal form is one which requires that all attributes have atomic domains.
24. What is nested relational model?
The nested relational model is an extension of relational model in which domains may be either atomic or relation valued.
25. List some instances of collection types?
*sets
*arrays
*multisets
26. How to create values of structured type?
Constructor functions are used to create values of structured types. A function with the same name as a structured type is a constructor function for the structured type.
27. Write a query to define tables students and teachers as sub tables of people?
Create table students of student under people
Create table teachers of teacher under people
28. What is a homogeneous distributed database?
In homogeneous distributed databases, all sites have identical database management system software, are aware of one another, and agree to cooperate in processing user's requests.
29. What is a heterogeneous distributed database?
In a heterogeneous distributed database, different sites may use different schemas, and different dbms s/w.The sites may not be aware of one another, and they may provide only limited facilities for cooperation in transaction processing.
30. What are the two approaches to store relations in distributed database?
*Replication
*Fragmentation
31. What are the two different schemes for fragmenting a relation?
*horizontal
*vertical
32. What is horizontal fragmentation?
Horizontal fragmentation splits the relation by assuming each tuple of r to one or more fragments.
33. What is vertical fragmentation?
Vertical fragmentation splits the relation by decomposing the scheme R of relation r.
34. What are the various forms of data transparency?
*fragmentation transparency
*replication transparency
*location transparency
35. Define decision tree classifiers?
As the name suggests decision tree classifiers use a tree: each leaf node has an associated class, and each internal node has a predicate associated with it.
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