Re: LOB Segments

From: Mark D Powell <>
Date: Thu, 16 Oct 2008 07:12:31 -0700 (PDT)
Message-ID: <>

On Oct 16, 12:51 am, DA Morgan <> wrote:
> wrote:
> >> Question: knowing a LOB segment contains just *column* data, why would
> >> a LOB column be treated differently from an ordinary column?
> > Umm, not quite what I meant...  I don't know what's any particular LOB
> > entry/segment.
> > An entry in a LOB column is a link to a LOB segment if the LOB is
> > larger than a certain size (4000 bytes I think), but if you archived/
> > exported/deleted that table would it also archive/export/delete the
> > LOB segments?
> > My guess is that it would, but that's why I'm asking.  I need to be
> > certain.
> For the purposes you are inquiring about the LOB segment may be
> thought of as part of the table just like the overflow of an IOT.
> --
> Daniel A. Morgan
> Oracle Ace Director & Instructor
> University of Washington
> (replace x with u to respond)
> Puget Sound Oracle Users

joshua, it is as Daniel said. If you export a table that has LOB columns you in effect also export the LOB segment(s).

If you delete the row in the table that has LOB columns you delete the associated LOB data also.

If you extract the base table row as part of an archive process then it is up to the developers to also extract and store the LOB data.

But Oracle's exp/imp, newer expdp/impdp are LOB aware and the sqlldr program can also load LOB data.

The point of my post being you have to consider the tool in use.

HTH -- Mark D Powell -- Received on Thu Oct 16 2008 - 09:12:31 CDT

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