--
Robert Fazio
Senior Technical Analyst
dbabob_at_yahoo.com
"Howard J. Rogers" <howardjr_at_www.com> wrote in message
news:3b75b62f_at_usenet.per.paradox.net.au...
>
> "Robert Fazio" <rfazio_at_home.com.nospam> wrote in message
> news:xNYc7.91101$EP6.22111132_at_news1.rdc2.pa.home.com...
> > From what I have read. Oracle doesn't allow for the system tablespace to
be
> > LM. Infact, if you read the docs on dbms_space_admin, you will see that
it
> > won't even allow system to be converted, but the say they will support
it
in
> > the future. The other two RBS and TEMP probably shouldn't be either.
TEMP
> > for example is already handled differently if set to type temporary,
plus
> > you want the ablity to change the extent management at a later time, if
you
> > choose LM, then you can't. RBS has the same issues.
> >
>
> I disagree, I'm afraid. Locally managed temp tablespaces are strongly
> supported and encouraged (indeed, in the 8i DBA course, the syntax example
> for creating a TEMP tablespace is pure LMT... they don't even mention the
> old, DMT, way of doing it.
>
Sorry, haven't been to DBA course in a while. That may be the case, but
that doesn't mean
that I agree with it. First of all Temp is already sort of locally managed.
There is no dictionary aspect to temp segments from what I do recall from my
past DBA classes. That is why you should have your temp tablespace as
temporary.
Consider the tuning aspect for both RBS and TEMP. Temp should always be a
multiple of the sort_area_size,
and they should have a fixed extent size.Tough to change if they are locally
managed with a fixed extent size thats wrong. Same goes for your RBS.
My point isn't that it is a bad idea, I am just a little more cautious with
something that can effect my system that dramatically. I do use LMT, but I
am just not ready to give up the control for those two just yet. Maybe
soon.
> The same is not true for Rollback Segment tablespace, but even there, I'd
> suggest that they are strongly recommended.
>
> Consider what LMTs are really good at: making massive extent allocation
and
> de-allocation of consistent sizes a trivially easy (and speedy) task.
> That's a prime requirement for rollback segments, since they have a
> propensity to grow and shrink all the time. It's also initially true for
> TEMP tablespace, as the temp segments are created by initial sorts.
>
> The only restriction of RBS tablespace as locally managed is that you must
> first create a rollback segment in dictionary managed tablespace (any one
> will do, even SYSTEM) to handle the DML that will take place to the new
> tablespace's bitmap when you create your first locally managed rollback
> segment. Once that first LMT rollback segment is online, the starter
> segment can be offlined and dropped, and all others can be created
normally.
>
> Regards
> HJR
>
>
>
>
> > Other than some early bugs related to the LM tablespaces, I do agree.
> >
> > --
> > Robert Fazio
> > Senior Technical Analyst
> > dbabob_at_yahoo.com
> >
> > "Howard J. Rogers" <howardjr_at_www.com> wrote in message
> > news:3b745321_at_usenet.per.paradox.net.au...
> > >
> > > "Kenneth Koenraadt" <plovmand_at_hotmail.com> wrote in message
> > > news:3b7197c5.7098447_at_news.mobilixnet.dk...
> > > >
> > > > On Tue, 7 Aug 2001 21:20:37 -0600, "Ron Gardiner"
> > > > <rongardiner_at_powersurfr.com> wrote:
> > > >
> > > > >New for 8i (I believe) is locally managed tablespaces...
> > > > >
> > > > >From what I've read, sounds like there is no reason NOT to use
them.
Can
> > > > >they be used for all types of TS?... rollback segs, temporary, how
about
> > > > >system itself?
> > > > >
> > > > >Any feedback would be appreciated!
> > > > >
> > > > >
> > > > >
> > > > Hi Ron,
> > > >
> > > > You cannot create a locally managed SYSTEM tablespace on database
> > > > creation. But you can convert it to LM later with a supplied
package.
> > > >
> > > > The SYSTEM tablespace and the tablespaces for rollback segments must
> > > > have the same extent management type, so if you convert the SYSTEM
> > > > Tablespace to LMT, rememer to convert your RBS tablespace(s) to LMT
as
> > > > well.
> > > >
> > >
> > > This is just not true.
> > >
> > > Firstly, whilst you may be able to convert SYSTEM into a LMT, it's
strongly
> > > advised not to. You may have noticed that SYSTEM also has 50%
PCTINCREASE,
> > > which is generally bad, and is autoextensible, which is also usually
> > > considered not terribly efficient... but the point is, SYSTEM breaks
all
the
> > > rules, and is best left to do so. LMT/DMT is just another example.
> > >
> > > Secondly, you appear to suggest that if SYSTEM is DMT, you must have
DMT
> > > rollback segment tablespace. Absolutely not true. Provided there is
one
> > > non-system rollback segment created (and brought online), you can
create
a
> > > LMT rollback tablespace, and create (and online) one LMT'd rollback
> > > segment... after which, the original DMT'd rollback segment can be
dropped,
> > > and all others created without a problem. And all of that can be done
> > > perfectly well with a SYSTEM tablespace that is merrily chugging a way
a
s
> > > dictionary-managed.
> > >
> > > Incidentally, the SYSTEM tablespace in 9i is still dictionary managed,
and
> > > there is still no provision for creating it Locally Managed... yet
another
> > > indication that locally managed SYSTEM tablespace is not advised, nor
> > > necessary.
> > >
> > > Regards
> > > HJR
> > >
> > >
> > >
> > >
> > > > Regards,
> > > > Kenneth Koenraadt
> > > > Systems Consultant
> > > > Oracle DBA
> > > > plovmand@<no-spam>hotmail.com
> > >
> > >
> >
> >
>
>
Received on Sat Aug 11 2001 - 18:45:33 CDT
