Re: Space and fragmentation in Oracle 7.3.4

A copy of this was sent to "Eric DUCHET" <eric.duchet_at_free.fr> (if that email address didn't require changing) On Thu, 02 Dec 1999 14:37:41 GMT, you wrote:

>Hi,
>
>I have a simple question:
>
>How Oracle recover the free space whenyou delete data from tables ?
>
>Is there any tools to compact a table online without doing an export/import
>?
>
>I have a table with 1 000 000 rows (1 extend) nad Initial Extend up to 100 M
>I delete all the rows from my table
>When I launch the query select count(*) ,
>it takes a lot of time.
>What does it mean ? Oracle makes a full scan of the table even if there is
>no data ?
>

a full scan reads all blocks upto the high water mark of a table. the HWM is never moved back for a delete -- a TRUNCATE will move the HWM back down. If you are deleteing all records - use truncate (it'll be faster, much faster). you cannot rollback a truncate like a delete.

>Thanx
>
>
>

--
See http://osi.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Part I of V, Autonomous Transactions" updated June 21'st  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Thu Dec 02 1999 - 08:55:59 CST