Database Administration - What is an Index ? How it is implemented in Oracle Database ?

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What is an Index ? How it is implemented in Oracle Database ?

An index is a database structure used by the server to have direct access of a row in a table.

An index is automatically created when a unique of primary key constraint clause is specified in create table comman (Ver 7.0)

Total Answers and Comments: 5

Last Update: August 17, 2007

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Submitted by: satyam_Ora

Indexes are used both to improve performence and to ensure uniquness of a column. Oracle automatically creates an index when a UNIQUE or PRIMARY key constarints clause is specified in a create table command.

We can manually create our own indexes via the create index command.

Above answer was rated as good by the following members:
kumarrajnishgupta

May 28, 2007 06:21:43

#1

sharada

RE: What is an Index ? How it is implemente...

hi

an index like index of book enables the database retreive and present data to end user with ease.An index can be defined as a mechanism for providing fast access to table rows and enforcing constraints

this is just definition i don't know how to implement

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June 30, 2007 18:39:52

#2

christine

RE: What is an Index ? How it is implemente...

You can implement index lihe this:
create index [index_name] on [Table_name]

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July 11, 2007 06:22:24

#3

sinu

RE: What is an Index ? How it is implemente...

Index is a database object it is used for improve table serarching operation (improve database perfomance) two types of index using oracle 1) bitmap index 2) btree index.

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August 17, 2007 21:22:16

#4

Member Since: July 2007 Contribution: 29

RE: What is an Index ? How it is implemente...

An index is a database structure used by the server to quickly find a row in a table.
In a relational database the physical location of row is irrelevent-unless of course the database needs to find it. In order to make it possible to find data each row in each table is labeled with ROWid. The row id tells the database exactly where the row is located.

Indexes contain a list of entries; each entry consists of a key value and a rowid The key value is the value of a column in a row or the combination of valuesof columns in a row.

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August 17, 2007 21:26:21

#5

Member Since: July 2007 Contribution: 29

RE: What is an Index ? How it is implemente...

Indexes are used both to improve performence and to ensure uniquness of a column. Oracle automatically creates an index when a UNIQUE or PRIMARY key constarints clause is specified in a create table command.

We can manually create our own indexes via the create index command.

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