Data Warehousing Community Forum
February 08, 2012, 10:33:19 pm

Pages: [1]   Go Down
« previous next »
  Print  
Author Topic: Index and its types...  (Read 1644 times)
Raj2007
DW Apprentice
**

Reputation: +3/-0
Offline Offline

Posts: 25


Lightning for DW Forum


View Profile
« on: July 02, 2007, 08:54:02 pm »
Hi,

An Index is an optional structure associated with a table to have direct access to rows, (with ROWID also, it can be done) which can be created to increase the performance of Data retrieval.

Index can be created on one or more coloumns of a table.

Can anybody tell me What is the type of Index that is used for Data Warehousing applications? Mention various types of Indexes also?
Logged
Sipra
Founder
*****

Reputation: +59/-0
Offline Offline

Posts: 323


Am the King...


View Profile WWW
« Reply #1 on: July 03, 2007, 10:45:30 am »
Your definition on Index is absolutely correct.

These are the following types of Indexes supported by Oracle.
  • B-Tree Indexes
  • B-Tree Cluster Indexes
  • Hash Cluster Indexes
  • Reverse Key Indexes
  • Bit-map Indexes

For all Data Warehousing applications, Bit-map Index is preferably used.
Logged
Sipra
Founder

www.dwforum.net
Whoever
Administrator
*****

Reputation: +34/-0
Offline Offline

Posts: 124



View Profile WWW
« Reply #2 on: July 03, 2007, 03:52:35 pm »
As you told,

Quote from: Sipra on July 03, 2007, 10:45:30 am
For all Data Warehousing applications, Bit-map Index is preferably used.

Why the Bit-map index is used for Data Warehousing applications ?

Is there is any specifc reason or advantages for using Bit-map Indexes?
Logged
If most people said what’s on their minds, they’d be speechless.
Sipra
Founder
*****

Reputation: +59/-0
Offline Offline

Posts: 323


Am the King...


View Profile WWW
« Reply #3 on: July 04, 2007, 12:46:54 pm »
Bit-map indexing benefits Data Warehousing applications which have large amounts of data and adhoc queries, but a low level of concurrent transactions.

For such applications, Bit-map indexing provides -

  • Reduced response time for large classes of adhoc queries.
  • A substantial reduction of space usage compared to other indexing techniques.
  • Dramatic performance gains even on very low end hardware.
  • Very efficient parallel DML and Loads.
Logged
Sipra
Founder

www.dwforum.net
Pages: [1]   Go Up
  Print  
« previous next »
 
Jump to: