Re: LMT with autoallocate

I'd just mention in passing that Steve Adams' website has an endorsement for UNIFORM extents as well. So when you get Jonathan Lewis, Steve Adams *and* Thomas Kyte all recommending UNIFORM... well, you get the idea (and I posted it first!!! ;-)

Regards
HJR

--
=============================!!=============================
The views expressed are my own only, and definitely NOT those of Oracle
Corporation
=============================!!=============================


"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in message
news:990570156.23295.1.nnrp-07.9e984b29_at_news.demon.co.uk...


>

> I have to agree with the bit that says 'there is a

> very good discussion ...' but the book does say:

>

> quote:

>

>     Frankly I have to say that I haven't yet thought of

>     any good reason for using tablespaces of the

>     AUTOALLOCATE type.

>

> unquote

>

> In fact, I think I have posted a bit on my website

> that qualifies this, and points out that for smaller

> scale databases using 3rd party apps, it could

> be a reasonable strategy when you have no

> control about which objects go in which

> tablespaces, and no information about which

> objects will be tiny and which will be huge.

>

> In cases where I am able to control the

> decision it's 100% uniform, but with

> a handful of different tablespaces and

> a small set of possibly UNIFORM sizes.

>

>

> --

> Jonathan Lewis

> Yet another Oracle-related web site:  http://www.jlcomp.demon.co.uk

>

> Practical Oracle 8i:  Building Efficient Databases

> Publishers:  Addison-Wesley

>

> Reviews at: http://www.jlcomp.demon.co.uk/book_rev.html

>

>

>

> Sybrand Bakker wrote in message ...

> >Comments embedded

> >

> >Hth,

> >

> >Sybrand Bakker, Oracle DBA

> >

> >"Vikas Agnihotri" <onlyforposting_at_yahoo.com> wrote in message

> >news:77e87b58.0105220927.432b49d8_at_posting.google.com...

> >> Since HJR doesnt have first-hand experience with autoallocate LMTs, I

> >> wanted to check if these beasts are used in real-world production

> >> databases at all.

> >

> >

> >Yes they are

> >

> >>

> >> Could someone who has used LMT (locally managed tablespaces) with

> >> either autoallocate or uniform extents comment on their alleged

> >> performance benefits, administrative issues, etc?

> >

> >Obviously, an enormous reduction of selects on fet$ and uet$ in system

> >(where dictionary managed tablespaces have their repository)

> >

> >In 8.1.6 however on Solaris there is a problem with exporting uniform

 LMTs:


> >this will result in EXP-0068. The data is exported though. Autoallocate

> >doesn't have this problem.

> >

> >

> >>

> >> Would you recommend LMT over dictionary managed?

> >

> >Yes

> >

> >

> >If so, would you

> >> recommend uniform or autoallocate?

> >>

> >

> >autoallocate. There is a very good discussion on this in Jonathan Lewis

 book


> >Practical Oracle 8i

> >Having extents bigger than can be read with 1 I/O request is according to

> >him more or less useless.

> >Oracle decides on whether it will use 64k or 1 M extents depending on

 O/S,


> >so you just shouldn't bother as long as you use maxextents unlimited.

> >

> >

> >

> >> Thanks...

> >

> >

>

>