Re: Disadvantages enable row movement

On 15 abr, 18:25, Mladen Gogala <mgogala.SPAM_ME...._at_verizon.net> wrote:
> On Sat, 14 Apr 2007 10:41:56 +0200, Matthias Hoys wrote:
> > Hello,
>
> > Flashback table requires that enable row movement is activated for the
> > table. By default, this is disabled. Are there any disadvantages by
> > enabling this for all tables (except that the ROWIDs might change) ?
> > Couldn't find much about this in the docs or with Google.
>
> > Oracle 10.2.0.3.
>
> > Matthias
>
> The only disadvantage is logical. ROWID used to be fixed value and I've
> seen some examples where ROWID has been used as a key to retrieve data,
> much like it's used in the EXCEPTIONS table. With row movement enabled,
> that stops making sense. Another situation in which row movement comes
> into play is partitioning. Row movement must be enabled if you need rows
> to move between partitions.
>
> --http://www.mladen-gogala.com

Just to add an example of what mladen has said, you can see:

http://carlosal.wordpress.com/2007/04/12/segment-space-management-y-high-watermark-en-10g/

It explains the SHRINK SPACE feature (which is another use of 'ENABLE ROW MOVEMENT), but shows what happen to ROWID's

HTH Cheers.

Carlos. Received on Mon Apr 16 2007 - 02:42:18 CDT