as an exceptional event. The warning sign is when queries that utilize nested
loops slow down without any apparent reason. The only case when index needs
to be rebuilt is the case of a table with frequent delete operations. You should consider rebuilding indexes if and only if the base table satisfies
that crieria. How to decide? There are few rules of thumb, none satisfactory
and decisive. I usually compare the number of blocks in the index with
the number of blocks in the table. If the number of blocks in the index
exceeds 50% of those in the table, the index is a candidate for rebuilding.
How did I come to 50%? I have no clue. That value popped up at one of my
previous jobs and I still use it, when I want to rebuild indexes. One of
the most frequent reasons for index rebuilding is a magazine reading boss
who has read that indexes need rebuilding. A script which rebuilds based on a criteria like 50% of the number of blocks usually satisfies damagement, especially if accompanied by a 3-page MS-Word document explaining this
hocus-pocus in detail. Picture of a B*-tree scanned from N. Wirth's "Data Structures+Algorithms = Programs" is a mandatory requirement for such documents.
On 2003.09.22 01:59, Veeraraju_Mareddi wrote:
Dear Friends,
Can somebody tell me how do we that an index needs to be rebuilt.. Different scenarios / any documents will be helpful.
Thanks in advance. Rajuvera ************************************************************************** This email (including any attachments) is intended for the sole use of the intended recipient/s and may contain material that is CONFIDENTIAL AND PRIVATE COMPANY INFORMATION. Any review or reliance by others or copying or distribution or forwarding of any or all of the contents in this message is STRICTLY PROHIBITED. If you are not the intended recipient, please contact the sender by email and delete all copies; your cooperation in this regard is appreciated. ************************************************************************** -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Veeraraju_Mareddi INET: [EMAIL PROTECTED]
Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
-- Mladen Gogala Oracle DBA -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mladen Gogala INET: [EMAIL PROTECTED]
Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
