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Rebuilding Indexes [message #331009] Wed, 02 July 2008 02:39 Go to next message
srini_thiru
Messages: 133
Registered: May 2008
Senior Member

Hi to all,

I have a doubt regarding index rebuilding.

I have analyzed one index with this

ANALYZE INDEX SR_INDEX_AK4 VALIDATE STRUCTURE.

When i queried Index_Stats Table i got the following result.

select height,name,lf_rows,del_lf_rows,(del_lf_rows/lf_rows)*100 "Percentage" from index_Stats;

HEIGHT NAME LF_ROWS DEL_LF_ROWS Percentage
4 SR_INDEX_AK4 61854857 5033 .00813679


After that i have rebuild the index using the command

ALTER INDEX ST_INDEX_AK4 REBUILD ONLINE;

After this command i again validated the index and used index_Stats to get the results

The result i got is,

HEIGHT NAME LF_ROWS DEL_LF_ROWS Percentage
4 SR_INDEX_AK4 61849824 0 0


Deleted rows has been removed but the height column remains 4.


What does it signifies.

I have read from the article if the height value is greater than 3 we have rebuild the indexes.


Can any one give me a clear idea about this.



Thanks in Advance,

Seenu

Re: Rebuilding Indexes [message #331020 is a reply to message #331009] Wed, 02 July 2008 02:59 Go to previous messageGo to next message
Michel Cadot
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It just means that it is useless, more dangerous, to rebuild indexes.

Quote:
I have read from the article if the height value is greater than 3 we have rebuild the indexes.

This is just wrong.

Regards
Michel
Re: Rebuilding Indexes [message #331033 is a reply to message #331009] Wed, 02 July 2008 03:32 Go to previous messageGo to next message
pablolee
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Location: Scotland
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Quote:
I have read from the article
You have read from what article? Can you post a link to it? Maybe you have mis-read, or read the statement out of context (but more than likely, as Michel says, the article is just plain wrong)
Re: Rebuilding Indexes [message #331061 is a reply to message #331009] Wed, 02 July 2008 04:35 Go to previous messageGo to next message
varu123
Messages: 754
Registered: October 2007
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May be OP read from dba-oracle.com.

Re: Rebuilding Indexes [message #331153 is a reply to message #331009] Wed, 02 July 2008 07:31 Go to previous messageGo to next message
srini_thiru
Messages: 133
Registered: May 2008
Senior Member


How can i determine that which indexes need rebuild.

Thanks in Advance,

Seenu
Re: Rebuilding Indexes [message #331171 is a reply to message #331153] Wed, 02 July 2008 08:19 Go to previous messageGo to next message
Michel Cadot
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At junior level, no one need to be rebuilt.

Regards
Michel
Re: Rebuilding Indexes [message #331205 is a reply to message #331009] Wed, 02 July 2008 10:15 Go to previous messageGo to next message
srini_thiru
Messages: 133
Registered: May 2008
Senior Member


I can't get you. Can you please explain this in detail.

Thanks,
Seenu
Re: Rebuilding Indexes [message #331210 is a reply to message #331205] Wed, 02 July 2008 10:22 Go to previous messageGo to next message
Michel Cadot
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There is no need to rebuild index (except in rare cases).
There is no indicator to automatically rebuild an index.
Why do you want to rebuild an index?

Regards
Michel
Re: Rebuilding Indexes [message #331212 is a reply to message #331205] Wed, 02 July 2008 10:27 Go to previous messageGo to next message
Mahesh Rajendran
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Just search this forum / google.
This is topic is asked and answered too many times.
Re: Rebuilding Indexes [message #331240 is a reply to message #331009] Wed, 02 July 2008 14:15 Go to previous messageGo to next message
srini_thiru
Messages: 133
Registered: May 2008
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The performance of our database is very slow. It takes long time to get the report from the tables.



Re: Rebuilding Indexes [message #331241 is a reply to message #331009] Wed, 02 July 2008 14:18 Go to previous messageGo to next message
BlackSwan
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http://www.orafaq.com/forum/t/88153/0/
Please read & follow posting guidelines as stated in URL above

http://www.orafaq.com/forum/t/84315/74940/
which of the suggestions in URL above have you tried & what were the results?

[Updated on: Wed, 02 July 2008 14:19] by Moderator

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Re: Rebuilding Indexes [message #331242 is a reply to message #331240] Wed, 02 July 2008 14:20 Go to previous messageGo to next message
Michel Cadot
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srini_thiru wrote on Wed, 02 July 2008 21:15
The performance of our database is very slow. It takes long time to get the report from the tables.

And what is the relation with index rebuilding?

Regards
Michel

Re: Rebuilding Indexes [message #331245 is a reply to message #331009] Wed, 02 July 2008 14:33 Go to previous messageGo to next message
srini_thiru
Messages: 133
Registered: May 2008
Senior Member


Actually i have a doubt regarding the indexes but its not related to peformance.

My other doubt is,

Our database performance is very slow. What are the steps i have to do, to check and change the database performance faster than now.

Re: Rebuilding Indexes [message #331246 is a reply to message #331245] Wed, 02 July 2008 14:34 Go to previous messageGo to next message
Michel Cadot
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ou can first read:
- OraFAQ Forum Guide, Performance Tuning section
- How to Identify Performance Problem and Bottleneck
- OraFAQ Performance Tuning
- Rosco's SQL Tuning Guide

You can also have a look at Database Performance Tuning Guide.

Regards
Michel
Re: Rebuilding Indexes [message #331248 is a reply to message #331245] Wed, 02 July 2008 14:35 Go to previous messageGo to next message
pablolee
Messages: 2834
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Location: Scotland
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Read and follow anacedent's 2nd link
Re: Rebuilding Indexes [message #331637 is a reply to message #331248] Fri, 04 July 2008 04:56 Go to previous messageGo to next message
ora110
Messages: 42
Registered: September 2007
Location: China
Member

It seems that we need not to rebuild index.
Re: Rebuilding Indexes [message #331652 is a reply to message #331637] Fri, 04 July 2008 06:16 Go to previous message
Michel Cadot
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Yes, it seems.

Regards
Michel
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