Tuesday, April 29, 2008

New Oracle Interview Questions Answers

New Oracle Interview Questions Answers

What are Clusters ?

Clusters are groups of one or more tables physically stores
together to share common columns and are often used together.

24. What is cluster Key ?

The related columns of the tables in a cluster is called the Cluster

25. What is Index Cluster ?

A Cluster with an index on the Cluster Key.

26. What is Hash Cluster ?

A row is stored in a hash cluster based on the result of applying a
hash function to the row's cluster key value. All rows with the same
hash key value are stores together on disk.

27. When can Hash Cluster used ?

Hash clusters are better choice when a table is often queried with
equality queries. For such queries the specified cluster key value
is hashed. The resulting hash key value points directly to the area
on disk that stores the specified rows.

28. What is Database Link ?

A database link is a named object that describes a "path" from one
database to another.

29. What are the types of Database Links ?

Private Database Link, Public Database Link & Network Database Link.

30. What is Private Database Link ?

Private database link is created on behalf of a specific user. A
private database link can be used only when the owner of the link
specifies a global object name in a SQL statement or in the
definition of the owner's views or procedures.

31. What is Public Database Link ?

Public database link is created for the special user group PUBLIC. A
public database link can be used when any user in the
associated database specifies a global object name in a SQL statement
or object definition.

32. What is Network Database link ?