Re: Table fragmentation

From: DA Morgan <damorgan_at_x.washington.edu>
Date: Thu, 13 Jan 2005 15:37:06 -0800
Message-ID: <41e70617$1_1@127.0.0.1>

Richard Foote wrote:

> "DA Morgan" <damorgan_at_x.washington.edu> wrote in message
> news:41e5cd68$1_2_at_127.0.0.1...
>

>>ibm_97_at_yahoo.com wrote:
>>
>>
>>>In 9.2.0.5, how can I detect if a table has blocks fragmentation or
>>>not? If it is, is exp/imp the only way to fix it?
>>>
>>>Thanks a lot!
>>
>>If you are in 9.2.0.5 you shouldn't have any so what is the actual issue?

>
>
> Hi Daniel
>
> If you delete a whole bunch of random rows and your PCTUSED value is not set
> correctly or if you simply don't re-insert the same volume of deleted rows,
> then a table could still be very well fragmented even in 10g. The result
> being "wasted" or unused space below the HWM of the table which might
> benefit from a rebuild if for example FTS performance were an issue.
>
> Rare, generally a result of a poor table definition, but still possible.
>
> Cheers
>
> Richard

I wasn't thinking of that as fragmentation ... just partially empty blocks. I tend to think of fragmentation more as being space where data can not be put because the number of available blocks is below the requirement for the next extent.

Thanks for pointing out the other meaning.

-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace 'x' with 'u' to respond)


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Received on Thu Jan 13 2005 - 17:37:06 CST