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To Tune or To use Hints (merged) [message #413462] Wed, 15 July 2009 20:21 Go to next message
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
Re: To Tune or To use Hints [message #413465 is a reply to message #413462] Wed, 15 July 2009 20:33 Go to previous messageGo to next message
BlackSwan
Messages: 25221
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.
Re: To Tune or To use Hints [message #413467 is a reply to message #413462] Wed, 15 July 2009 20:53 Go to previous messageGo to next message
BlackSwan
Messages: 25221
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]

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Re: To Tune or To use Hints [message #413470 is a reply to message #413467] Wed, 15 July 2009 22:36 Go to previous messageGo to next message
rleishman
Messages: 3727
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
Re: To Tune or To use Hints (merged) [message #413473 is a reply to message #413462] Wed, 15 July 2009 23:20 Go to previous message
Michel Cadot
Messages: 64425
Registered: March 2007
Location: Nanterre, France, http://...
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]

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