further issues

"Howard J. Rogers" <hjr_at_dizwell.com> wrote in message news:<40b88fcb$0$8984$afc38c87_at_news.optusnet.com.au>...
> "yls177" <yls177_at_hotmail.com> wrote in message
> news:c06e4d68.0405290510.40d41c4a_at_posting.google.com...
>
> > > For DMT, you can *try* to help things along by specifying MINIMUM EXTENT
> for
> > > a tablespace. That is not part of the default storage clause, and
> therefore
> > > cannot be overridden by anything in the segment's specific storage
> clause.
> > > However, it still doesn't do the job, because it is *interpreted* in the
> > > light of a segment-specific storage clause. If minimum extent is 500K,
> and
> > > your segment requests an initial of 23K, it will be given 500K. But if
> the
> > > segment then asks for a next of 612K, it will be given a 1MB extent...
> at
> > > which point, initial does not equal next for that tablespace. It
> certainly
> > > means you have less variation in extent sizes, however, and is therefore
> the
> > > next best thing to using LMTs.
> >
> >
> > after the segment requests for an initial of 23k, 377k still remains
> > in the extent. if another new segment requests for 70K, will it use
> > the same segment as the 23K or a total new extent will be given?
>
> Remember: an extent belongs exclusively to a segment. If one segment is
> allocated 500K, uses 23K and has 377K of free space in the extent still to
> go (though I think mathematics suggests it might be more like 477K), that
> has absolutely nothing to do with the second new segment. If it requests
> 70K, it will be given a brand new extent of 500K. Segments don't share
> extents.
>

thanks for the clarification... but say now , there are some DML statements which reduce the segment size from 23K to 20K, then there will be "holes" in this extent which are known as fragmentation?

also, what happens now if a segment is asking for 700K? 1MB extent will be given as discussed earlier. but is this 1MB extent a single 1MB extent or 2 500K extents?

finally, u guys are right.. its 1.5TB, i made a typo error, 1.5GB is not huge at all.. since our personal computer hardisk can easily hit over that size.

cheers

> > also, a 1MB extent is given because the new segment is asking for a
> > 612K, whereas the minimum extent size is 500K, therefore it is not
> > sufficient and hence 2 is needed or 1 extent with a size of 1MB? .
> > which means to say that the extent size are not uniform which is
> > fragmentation
> > >
> > > You can retrofit a DMT tablespace with a MINIIMUM EXTENT clause (alter
> > > tablespace X minimum extent Y). But that doesn't do anything for the
> extents
> > > within the tablespace that have already been allocated, of course.
> > >
> >
> > here, u were saying that the above sql command is not valid for those
> > extents that have already been allocated?
>
> It's not "not valid". It's a perfectly legitimate bit of SQL, that will be
> accepted at any time. But it won't cause the tablespace to re-size those
> extents which have already been allocated. They will still have their
> original sizes, even if they are extremely weird and have not the slightest
> resemblance to a new MINIMUM EXTENT clause.
>
> Regards
> HJR
>
>
>
> > > Regards
> > > HJR
Received on Sun May 30 2004 - 20:09:34 CDT