Re: Any single SQL clause to release the unused space under high water mark in table.

"Chuan Zhang" <chuan_at_asiaonline.net> wrote:
>Hi, All,
>
> As I know, there is command "alter table "tablename"
 deallocated unused "
>which will release all the unused space above high water mark.
 However, as I
>know, there is not one to release the unused space under HWK.
>
>I know, I can export or copy that table, truncate it, then
 import or recopy
>it to release that unused space.
>However, since I am in production environment, we might lose
 data by doing
>this.
>
>Any clues or suggestion to do this would be much appreaciated,
>
>Thanks in advance,
>
>Chuan Zhang
>

There is no command to release space below the high water mark. As a DBA you manage how Oracle uses this space by carefully considering the settings for pctfree and pctused at object creation and rebuild. You can chage these factors at any time and they will become effective on the next block access though Oracle will not move data around because of the parameter value changes. A select * from the_table will cause blocks to be added/deleted from the free list(s) and can help to manage the reuse of allocated space. Freelists, freelist groups, and initrans also come into play and should also be considered. The Oracle 8i Concepts manual has a good chapter on these parameters.

• Mark D. Powell -- The only advice that counts is the advice that you follow so follow your own advice. --

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http://www.keen.com Received on Mon Aug 14 2000 - 08:50:46 CDT