indexes

[anish jain]

Please explain how does the index work in database?

[Janeice DelVecchio]

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.

[anish jain]

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]

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