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Indexes In SQL Server

What Do I Need On My System?

What Are Technical Concepts I Need To Know?

  1. What are tables in SQL server?
  2. What is a primary key?

What Is A Database Index?

  1. Index is a data structure
  2. Index helps in speeding up the data retrieval operations
  3. Additional cost and storage space is required to maintain index

Types Of Database Index In SQL Server

  1. Clustered index
  2. Non-clustered index

How Physical Sorting And Logical Sorting Are Different


Picture showing the graphical representation of the b-tree

Cluster Index

  1. Only one clustered index per table
  2. Data is stored in leaf node of B-Tree. All other nodes contain index rows
  3. Data is physically sorted

-- Syntax for creating clustered index
CREATE CLUSTERED INDEX index_name ON table_name (column_name)

Non-Clustered Index

  1. More than one non-clustered index can be implemented on a table
  2. Leaf node of B-Tree contains the address of data
  3. Data is logically sorted

-- Syntax for creating non clustered index
CREATE NONCLUSTERED INDEX index_name ON table_name (column_name)

Posted By  -  Karan Gupta
Posted On  -  Wednesday, January 28, 2015


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