Glenn,

Here you go..

1) This is a rebuild of the table, sort of export/import. All rows get new
rowids and that's why all indexes need re-creating.

2) It will not lower the HWM. It frees up space between the HWM and last
allocated extent. HWM is adjusted only when the table is rebuilt or is
truncated.

Hope this helps.

Regards.

- Kirti Deshpande
Verizon Information Services
http://www.superpages.com

> -----Original Message-----
> From: Glenn Travis [SMTP:c-glenn.[Email Address Removed] Sent: Tuesday, July 31, 2001 10:17 AM
> To: LazyDBA.com Discussion
> Subject: RE: High Water Mark !!
>
> So here's the next question you'll see. As we all know, Oracle will read
> up
> to the high water mark on table scans. So, how do you lower the high
> water
> mark without exp/imp?
>
> 1) alter table tab1 move...
> - will this rebuild the table or just move all the allocated pages?
> - I know it invalidates the indexes and they will need to be rebuilt
> so I
> am assuming the table is rebuilt...
>
> 2) alter table tab1 deallocate unused?
> - will this free up the allocated and unused pages and lower the HW
> mark?
>
> anyone?
>
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