Question 26 :
What are Clusters ?
Clusters are groups of one or more tables physically stores together to share common columns and are often used together.
Question 27 :
What is an Integrity Constrains ?
An integrity constraint is a declarative way to define a business rule for a column of a table.
Question 28 :
What is an Index ?
An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
Question 29 :
What is an Extent ?
An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.
Question 30 :
What is a View ?
A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)