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The moose likes Oracle/OAS and the fly likes indexes Big Moose Saloon
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indexes

anish jain
Ranch Hand

Joined: Feb 03, 2010
Posts: 129
Please explain how does the index work in database?
Janeice DelVecchio
Saloon Keeper

Joined: Sep 14, 2009
Posts: 1732
    
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The index in a database works in the same way an index would work in a book. It's a way for the DB to retrieve data faster.

In Oracle you can make your own indexes for columns you use a lot, but some are made automatically for columns with Primary Key constraints or Unique constraints.


When you do things right, people won't be sure you've done anything at all.
anish jain
Ranch Hand

Joined: Feb 03, 2010
Posts: 129
Janeice DelVecchio wrote:The index in a database works in the same way an index would work in a book. It's a way for the DB to retrieve data faster.

In Oracle you can make your own indexes for columns you use a lot, but some are made automatically for columns with Primary Key constraints or Unique constraints.


Can you please elaborate? I want to know how does that work when someone fires a select query?
Tom Reilly
Rancher

Joined: Jun 01, 2010
Posts: 618
Can you please elaborate? I want to know how does that work when someone fires a select query?


Every database implementation is different. Here's a link that explains how Oracle database does it: http://www.dba-oracle.com/art_9i_indexing.htm
 
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subject: indexes