What are indexes? When do you need to create Indexes?

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What are indexes? When do you need to create Indexes?..

Answer / bhagwat sharma

When data volumes increase, organizations are faced with
problems relating to data retrieval and posting. They feel
the need for a mechanism that will increase the speed of
data access. An index, like the index of a book, enables the
database retrieve and present data to the end user with
ease. An index can be defined as a mechanism for providing
fast access to table rows and for enforcing constraints.

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What are indexes? When do you need to create Indexes?..

Answer / rajeev

Index is used for fast searching and batter performance.

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What are indexes? When do you need to create Indexes?..

Answer / murtaza

INDEXES:
1.indexes are used for performance as well as query
optimization issues in database.
2.indexes are by default created when u create an primary or
unique index on a particular column in a table.
3.In sql server there are 2 types of indexes
1.clustered index
2.non clustered index
4.By default non clustered index are created in sql server 2005.
WHEN TO CREATE INDEXES:
1.indexes should be created on the tables which will be used
frequently.
2.it should be created on d tables which has large amount of
data.

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What are indexes? When do you need to create Indexes?..

Answer / radhakrishnan

index : increase the performance of sql statement.

When we create :
1) large number of data in table
2) most of null value in specific column
3) multiple join in sql statement
4) less than 2% of data retrive from table

when we not create :
1) frequently update the table
2) less number of data

Type of Index :
1) clustered index
- primary & unique constaint cretae autoatically for this
index
- only one clustered index per table.
- data sorted physical order
- Eg : book front index
2) non clustered index
- create multiple index per table.
- Eg : book back index

Syntax :

Create index index_name on tablename (column name)

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