Re: LMT with autoallocate

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...

>

>