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Question 26 :

What are Clusters ?

Answer :

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 ?

Answer :

An integrity constraint is a declarative way to define a business rule for a column of a table.


Question 28 :

What is an Index ?

Answer :

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 ?

Answer :

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 ?

Answer :

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.)