OraFAQ Forum: Performance Tuning » To Tune or To use Hints (merged)

Home » RDBMS Server » Performance Tuning » To Tune or To use Hints (merged)

Show: Today's Messages :: Polls :: Message Navigator
E-mail to friend

To Tune or To use Hints (merged) [message #413462]

Wed, 15 July 2009 20:21

ap_karthi
Messages: 87
Registered: October 2007
Location: Bangalore

Member

Hello,

1. A Table contains 40 columns and 20 million rows(records).
Only one column have '*' (asterisk) as data in all the 20 million rows for some reason.
2. When I ran Oracle Tuning Advisor in Toad, it says create an index for this column which contains '*'.

3. My question is what type of index should be created?
4. Whether /*+HINTS*/ will be helpful?
Pls suggest. Thanks

-Karthik

Report message to a moderator

Re: To Tune or To use Hints [message #413465 is a reply to message #413462]

Wed, 15 July 2009 20:33

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

>. When I ran Oracle Tuning Advisor in Toad, it says
If it told you to stand on your head in the corner of the room,
would you do so?

Is this column used in any WHERE clause?
If not, then no index is needed.
If so, post the SQL.

Report message to a moderator

Re: To Tune or To use Hints [message #413467 is a reply to message #413462]

Wed, 15 July 2009 20:53

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

Follow Posting Guidelines & do not cross/multi-post!

You need to help us by following the Posting Guidelines as stated below.
http://www.orafaq.com/forum/t/88153/0/
Go to the URL above click the link "Posting Guidelines"
Go to the section labeled "Practice" & do as directed.

[Updated on: Wed, 15 July 2009 20:57]

Report message to a moderator

Re: To Tune or To use Hints [message #413470 is a reply to message #413467]

Wed, 15 July 2009 22:36

rleishman
Messages: 3728
Registered: October 2005
Location: Melbourne, Australia

Senior Member

An index will only speed up identifiction of a REDUCED row set. If every row has the same value, then any WHERE clause you apply on the column will not reduce the results. An index is likely to be useless.

Ross Leishman

Report message to a moderator

Re: To Tune or To use Hints (merged) [message #413473 is a reply to message #413462]

Wed, 15 July 2009 23:20

Michel Cadot
Messages: 68716
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

I recommend you to read:
- Performances -Tuning sticky and link related to indexes
- Database Performance Tuning Guide
- http://www.orafaq.com/forum/m/382787/102589/

Regards
Michel

[Updated on: Wed, 15 July 2009 23:35]

Report message to a moderator

Previous Topic:	Enable 10053 Trace information
Next Topic:	Force the optimizer to use the primary key index

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

]

Current Time: Mon Nov 25 22:11:33 CST 2024